[identity] rename and dedup more tonic Status messages
Summary:
there are a lot of tonic status messages that need to be converted to snake_case and dedup'd.
i've arbitrarily broken this work up into chunks to make it easier to review
Depends on D12401
Test Plan: git grep for the old status messages, change client error handling where needed
Reviewers: bartek
Reviewed By: bartek
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D12402