Catch regex config errors in AWS proxy; fix logic for proxying S3 requests with host-based addressing

[whummer]

Adjust regex logic to catch config errors in AWS proxy.

Addresses an issue where we've recently seen errors like this:

  File "/var/lib/localstack/lib/extensions/python_venv/lib/python3.11/site-packages/aws_replicator/server/aws_request_forwarder.py", line 74, in select_proxy
    resource_name_matches = any(
                            ^^^^
  File "/var/lib/localstack/lib/extensions/python_venv/lib/python3.11/site-packages/aws_replicator/server/aws_request_forwarder.py", line 75, in <genexpr>
    self._request_matches_resource(context, resource_name_pattern)
  File "/var/lib/localstack/lib/extensions/python_venv/lib/python3.11/site-packages/aws_replicator/server/aws_request_forwarder.py", line 105, in _request_matches_resource
    return bool(re.match(resource_name_pattern, s3_bucket_arn))
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/re/__init__.py", line 166, in match
    return _compile(pattern, flags).match(string)
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/re/__init__.py", line 294, in _compile
    p = _compiler.compile(pattern, flags)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/re/_compiler.py", line 745, in compile
    p = _parser.parse(p, flags)
        ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/re/_parser.py", line 989, in parse
    p = _parse_sub(source, state, flags & SRE_FLAG_VERBOSE, 0)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/re/_parser.py", line 464, in _parse_sub
    itemsappend(_parse(source, state, verbose, nested + 1,
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.11/re/_parser.py", line 691, in _parse
    raise source.error("nothing to repeat",
re.error: nothing to repeat at position 0

We are not changing the logic per se in here, but at least make the error message more human-readable.

---

The PR also enhances the logic for proxying S3 requests with host-based addressing. This is required for AWS SDK S3 clients that are using host-based bucket addressing (e.g., AWS JavaScript SDK v2/v3 by default). We are now passing a x-ls-host-original from the original request handler to the proxy handler, and then extract the bucket name from that header value, to form the final request path (/<bucket>/<path>).

The tests have been extended with additional parametrization to cover this case (host-based as well as path-based bucket addressing) as well.