R1:fd12b37d16f6

Modularize Repository transactions

Summary: Depends on D19828. Ref T13216. Before adding new transactions to repositories (filesize limit, copy time limit, etc) modularize the existing transactions.

Test Plan:

- Created repository.
- Edited callsign (invalid, valid, duplicate, add, remove).
- Edited short name (invaild, valid, duplicate, add, remove).
- Edited description (add, remove).
- Edited encoding (invalid, valid, remove).
- Allowed/denied dangerous changes.
- Allowed/denied enormous chagnes.