Pass the source's SSE-C and RequestPayer parameters to the lookups of copies and setxattr #1333

Part of #1327 (defect 1 of the audit report).

Summary

Copies and metadata replacement look up the source object without the authorization parameters that the call carries, so an SSE-C source, or a requester-pays source with a per-call RequestPayer, cannot be copied: the lookup fails before CopyObject is sent.

Scenario

fs.cp_file(src, dst,
           CopySourceSSECustomerAlgorithm="AES256", CopySourceSSECustomerKey=key,
           SSECustomerAlgorithm="AES256", SSECustomerKey=key)

Expected: the copy succeeds. S3Core already maps these parameters to the source lookups (S3Core._copy_source_params), and plan_multipart_copy uses that mapping.
Actual: HeadObject is sent with only Bucket and Key; S3 answers 400 for an SSE-C object, which surfaces as OSError(EINVAL). Whether it fails depends on the cache: a cached parent listing answers info() without a request.

Affected paths (at 766d79d)

1. S3FileSystem._copy_file: info1 = self.info(path1) (s3.py:1604), and the same in AioS3FileSystem._copy_file (s3_async.py:576).
2. S3FileSystem._move_pairs: self._head_object(source) (s3.py:1440) for the conflict check of mv.
3. mv's delete of the copied sources receives none of the call's parameters (s3.py:1398).
4. setxattr: head = self.metadata(path) (s3.py:2132) without the lookup parameters of copy_kwargs.

The existing test test_copy_object_with_multipart_upload_sse_c_source calls _copy_object_with_multipart_upload directly and skips the lookup.

Fix direction

Make the source-lookup mapping a public S3Core method next to the destination-side operation_params, and pass its result to every source lookup above, in both filesystems; pass DeleteObjects-accepted parameters to mv's delete. Reproduced offline with botocore's Stubber: the HeadObject request of cp_file, setxattr, and cp_file(..., RequestPayer="requester") carried only Bucket and Key.