R1:29d1115037b8

Swap Repository Edit UI to new code

Summary:
Ref T10748. This needs more extensive testing and is sure to have some rough edges, but seems to basically work so far.

Throwing this up so I can work through it more deliberately and make notes.

Test Plan:
- Ran migration.
- Used `bin/repository list` to list existing repositories.
- Used `bin/repository update <repository>` to update various repositories.
- Updated a migrated, hosted Git repository.
- Updated a migrated, observed Git repository.
- Converted…