REST catalog: support AWS sigV4

[xxchan]

Is your feature request related to a problem or challenge?

For AWS glue/s3 tables

rest.sigv4-enabled, rest.signing-name, rest.signing-region

apache/iceberg-python#1405

rest_catalog = load_catalog(
  catalog_name,
  **{
    "type": "rest",    
    "warehouse":"arn:aws:s3tables:<Region>:<accountID>:bucket/<bucketname>",
    "uri": "https://s3tables.<Region>.amazonaws.com/iceberg",
    "rest.sigv4-enabled": "true",
    "rest.signing-name": "s3tables",
    "rest.signing-region": "<Region>"
  }
)                

Describe the solution you'd like

No response

Willingness to contribute

None

[xxchan]

Found a problem in reqsign:

1. Reqsign got canonical request like: canonical request: GET /iceberg/v1/arn%3Aaws%3As3tables%3Aap-southeast-1..., but should have been sth like /iceberg/v1/arn%253Aaws%253As3tables%253Aap-southeast-1%..., where reqsign wrongly decoded %3.
2. x-amz-content-sha256 seems to be required for this endpoint, which is not natively supported by reqsign.

[ananthaksr]

@xxchan I'd like to work on this.

[xxchan]

@ananthaksr Hi, thanks for offering help, but I've already finished a working draft. #1241