Slightly modernize all Diffusion edit endpoints
Summary: Ref T4245. Prepares edit endpoints for more flexible repository identifiers.
Test Plan:
- Added, edited, deleted mirror.
- Created repository.
- Edited basic repository information.
- Edited policies for a repository.
- Activated/deactivated repository.
- Updated a repository.
- Hit "Delete" dialog for a repository.
- Edited hosting.
- Toggled dangerous changes.
- Edited branches.
- Edited automation.
- Tested automation.
- Edited storage.
- Edited staging.
- Edited encoding.
- Edited symbols.
- Edited branches.
- Edited actions.
- Tried to do edits as an unprivileged user.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T4245
Differential Revision: https://secure.phabricator.com/D14945