feat: Use DH S3Instructions to build Iceberg AWS clients

[deephaven-internal]

This issue was auto-generated

PR: deephaven/deephaven-core#6113
Author: devinrsmith

Original PR Body

This provides a way for users who are responsible for providing AWS / S3 credentials to specify it in a way where Deephaven can own the S3 client building logic for the Iceberg Catalog in additional to our own data access layer.

Note, this does not deprecate DataInstructionsProviderPlugin, as there may be cases where the user is not responsible for providing these credentials, and it is instead provided via the catalog after catalog authorization. See #6191