Add more metadata fields to FileMetadata

[damccorm]

We currently only have "path" and "size_in_bytes" to FileMetadata. We could add additional arguments such as:

• mime type
• permissions
• data hash (such as Etag from S3)
• date created
• date updated

Imported from Jira BEAM-10105. Original Jira may contain additional context.
Reported by: epicfaace.