Add support for AWS Glue's implementation of Iceberg REST Catalog API

[mdub]

We recently added basic support for the Iceberg REST Catalog API (commit 000ff95), but it won't work with AWS Glue REST Catalog endpoints like:

https://glue.us-west-2.amazonaws.com/iceberg/v1/catalogs/979779072649

AWS Glue REST endpoints require AWS Signature Version 4 (SigV4) for authentication.

[mdub]

Unfortunately, iceberg-catalog-rest 0.7.0 currently lacks SigV4 support. There's an open issue:

• REST catalog: support AWS sigV4 apache/iceberg-rust#1236