Iceberg Rest Catalog does not honor "s3.signer.uri" property

[c-thiel]

Apache Iceberg version

main (development)

Please describe the bug 🐞

The primary way of the Iceberg REST Catalog to grant access to S3 tables is remote signing.
This is currently not implemented for FileIO - which is another issue.

When using FSSPEC, the "s3.signer.uri" property is currently not respected. This is a useful property in a multi-tenant or maybe even multi-region catalog setup, where the S3 signer should stay close to the data / client.