[Observability] Integrate OpenTelemetry

[TedaLIEz]

Summary

This pull request introduces OpenTelemetry (OTel) support to the project, including configuration settings, initialization, and integration with various components.

OpenTelemetry Integration:

• api/.env.example: Added configuration settings for enabling and configuring OpenTelemetry.
• api/app_factory.py: Included ext_otel in the list of extensions to initialize OpenTelemetry. [1] [2]
• api/configs/app_config.py: Imported and added ObservabilityConfig to the configuration. [1] [2]
• api/configs/observability/__init__.py: Created ObservabilityConfig class inheriting from OTelConfig.
• api/configs/observability/otel/otel_config.py: Defined OTelConfig class with various OpenTelemetry configuration settings.
• api/extensions/ext_otel.py: Implemented init_app function to initialize OpenTelemetry and set up context propagation and shutdown procedures.
• api/pyproject.toml: Added OpenTelemetry dependencies.

Docker Configuration:

• docker/.env.example: Added OpenTelemetry configuration settings to the Docker environment example file. [1] [2]
• docker/README.md: Updated documentation to include OpenTelemetry setup instructions. [1] [2]
• docker/docker-compose.yaml: Added OpenTelemetry environment variables to the shared API worker environment.

By default, the opentelemetry is off. You can turn it on in .env

Screenshots

Before	After
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Checklist

Important

Please review the checklist below before submitting your pull request.

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[crazywoola]

Please resolve the conflicts.

[TedaLIEz]

@crazywoola Conflicts have been resolved.

[crazywoola]

LGTM