[TRB46642]: refactoring hydra endpoint

[michaelscrawford]

Intent

Refactor the existing (redunant) path that points to our underlying Hydra server

Background

• We should not specify the name hydra in the public API as that exposes the implementation (which may well change)
• There is no 'standard' path, but both Hydra and AWS use /oauth2/token; I suggest we follow suit.

1. Hydra: /oauth2/token/
2. AWS: /oauth2/token/
3. GCP: /oauth2.googleapis.com/token/
4. Facebook: /oauth/access_token/

Testing

(any manual resting performed, along with log outputs and screenshots as appropriate)

Checklist

These are the items that must be done by the developer and by reviewers before the change is ready to merge. Please strikeout any items that are not applicable, but don't delete them

• [ ] Developer Checks
  • [ ] Full build with unit tests and fmt and vet checks
  • [ ] Unit tests added / updated
  • [ ] No unlicensed images, no third-party code (such as from StackOverflow)
  • [ ] Integration tests added / updated
  • [ ] Manual testing done (and described)
  • [ ] Product sweep run and passed
  • [ ] Developer wiki updated (and linked to this description)
• [ ] Reviewer Checks
  • [ ] Merge request description clear and understandable
  • [ ] Developer checklist items complete
  • [ ] Functional code review (how is the code written)
  • [ ] Architectural review (does the code try to do the right thing, in the right way)
  • [ ] Defensive coding (incoming data checked / sanitized, exceptions logged, clear error messages)
  • [ ] No unlicensed images, no third-party code (such as from StackOverflow)
  • [ ] Security review checklist complete.

Audience