R1:7c98cd85fe6d

Implement DestructibleInterface for Owners Packages

Summary:
Fixes T9945. This is straightforward.

The two sub-object types are very lightweight so I just deleted them directly instead of loading + delete()'ing (or implementing DestructibleInterface on them, which would require they have PHIDs).

Also improve a US English localization.

Test Plan:
- Used `bin/remove destroy PHID-... --trace` to destroy a package.
- Verified it was gone.
- Inspected the SQL in the log for general reasonableness.