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

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](https://docs.aws.amazon.com/glue/latest/dg/connect-glu-iceberg-rest.html) require AWS Signature Version 4 (SigV4) for authentication.