Media cluster origin

[caiosba]

Description

Adding a cached field to ProjectMedia items, also exposed in the GraphQL ProjectMediaType, called media_cluster_origin, which explains how that media ended up in that particular media cluster.

Steps:

• Media cluster origin library, with all possible values represented by different constants.
• Expose in GraphQL ProjectMediaType.
• Implement logic as cached field for the different cases:
  • Initial / Empty state.
  • Tipline submission.
  • User submitted.
  • User merged.
  • User confirmed.
  • Auto matched.
• Implement automated tests.

References: CV2-5933.

How has this been tested?

Automated tests implemented for 100% code coverage.

Checklist

• I have performed a self-review of my own code
• I have added unit and feature tests, if the PR implements a new feature or otherwise would benefit from additional testing
• I have added regression tests, if the PR fixes a bug
• I have added logging, exception reporting, and custom tracing with any additional information required for debugging
• I considered secure coding practices when writing this code. Any security concerns are noted above.
• I have commented my code in hard-to-understand areas, if any
• I have made needed changes to the README
• My changes generate no new warnings
• If I added a third party module, I included a rationale for doing so and followed our current guidelines