Rewrote Bibucket provider tests (1/3)
Rewrote Bibucket provider tests (1/3)

- Added or modified
  - file metadata, file download
  - folder metadata, folder contents
  - file histories, file last commit
  - path from metadata
- Removed: file metadata cache (no longer relevant)
- TODO:
  - main branch
  - path validation

CenterForOpenScience/waterbutler,felliott/waterbutler