Obtain metadata field at once in file system's IO connectors

[damccorm]

This tasks involves refactoring and improvements of IO connectors' file metadata related methods (GcsIO, S3IO, BlobIO, hadoop).

Currently, we have individual methods like size, last_updated, checksum, and others. Each one would make a HTTP request in order to get the specific metadata field. If one needs to gather multiple metadata fields, then every specific method are called and making multiple requests under the hood. Actually, the HTTP response contains multiple file metadata fields but each time only one field is collected and others are discarded.

We should have a public method that returns a named tuple which contains multiple file metadata fields. In its implementation it only makes one request, as existing methods for single metadata field. 

 

Imported from Jira BEAM-14393. Original Jira may contain additional context.
Reported by: yihu.