[Draft, do not merge] Entities Prototype

[tigrannajaryan]

Changes

• Added entity refs to the Resource representation.
• Made default Service detector produce a Resource with "service" entity type.
• Modified stdout exporters to include entity information in the output.
• Modified Resource.Merge() to use the new logic that takes the entities into account.
• Added resource.NewWithEntities() to allow creating resources with entities.
• Updated OTLP exporters to include entity info in the Resource.
• Modified some existing resource some detectors to include entities (WithProcess, WithHostID) and added WithHostEntity to demonstrate how detectors work.

Results

Example output from dice example is below.

Note EntityRefs under the Resource.

{
        "Resource": {
                "Attributes": [
                        {
                                "Key": "host.id",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "4A135D30-F122-5869-9399-30339FDAE584"
                                }
                        },
                        {
                                "Key": "host.name",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "KYW9LWX6YV"
                                }
                        },
                        {
                                "Key": "process.command_args",
                                "Value": {
                                        "Type": "STRINGSLICE",
                                        "Value": [
                                                "/Users/tnajaryan/Library/Caches/JetBrains/GoLand2024.2/tmp/GoLand/___go_build_go_opentelemetry_io_otel_example_dice"
                                        ]
                                }
                        },
                        {
                                "Key": "process.executable.name",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "___go_build_go_opentelemetry_io_otel_example_dice"
                                }
                        },
                        {
                                "Key": "process.executable.path",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "/Users/tnajaryan/Library/Caches/JetBrains/GoLand2024.2/tmp/GoLand/___go_build_go_opentelemetry_io_otel_example_dice"
                                }
                        },
                        {
                                "Key": "process.owner",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "tnajaryan"
                                }
                        },
                        {
                                "Key": "process.pid",
                                "Value": {
                                        "Type": "INT64",
                                        "Value": 91752
                                }
                        },
                        {
                                "Key": "process.runtime.description",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "go version go1.23.2 darwin/arm64"
                                }
                        },
                        {
                                "Key": "process.runtime.name",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "go"
                                }
                        },
                        {
                                "Key": "process.runtime.version",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "go1.23.2"
                                }
                        },
                        {
                                "Key": "service.name",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "dice"
                                }
                        },
                        {
                                "Key": "service.version",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "0.1.0"
                                }
                        },
                        {
                                "Key": "telemetry.sdk.language",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "go"
                                }
                        },
                        {
                                "Key": "telemetry.sdk.name",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "opentelemetry"
                                }
                        },
                        {
                                "Key": "telemetry.sdk.version",
                                "Value": {
                                        "Type": "STRING",
                                        "Value": "1.23.0-rc.1"
                                }
                        }
                ],
                "SchemaURL": "https://opentelemetry.io/schemas/1.24.0",
                "EntityRefs": [
                        {
                                "Type": "service",
                                "Id": [
                                        "service.name",
                                        "service.version"
                                ],
                                "Attrs": null,
                                "SchemaURL": "https://opentelemetry.io/schemas/1.24.0"
                        },
                        {
                                "Type": "host",
                                "Id": [
                                        "host.id"
                                ],
                                "Attrs": [
                                        "host.name"
                                ],
                                "SchemaURL": "https://opentelemetry.io/schemas/1.24.0"
                        },
                        {
                                "Type": "process",
                                "Id": [
                                        "process.pid"
                                ],
                                "Attrs": [
                                        "process.runtime.description",
                                        "process.executable.name",
                                        "process.executable.path",
                                        "process.command_args",
                                        "process.owner",
                                        "process.runtime.name",
                                        "process.runtime.version"
                                ],
                                "SchemaURL": "https://opentelemetry.io/schemas/1.24.0"
                        }
                ]
        },
        "ScopeMetrics": []
}

[tigrannajaryan]

I updated this PR to make Resource comparable as required by #6272