R1:859b27497095

Provide more information to users during `git push` while waiting for write locks

Summary:
Ref T13109. Make it slightly more clear what the scope of the write and read locks are, and slightly more clear that we're actively acquiring locks, not just sitting around waiting.

While waiting on another writer, show who we're waiting on so you can walk over to their desk and glare at them.

Test Plan:
Added `sleep(15)` after `willWrite()`. Pushed in two windows. Saw new, more informative messages. In the second…