R1:be235301d0dc

When commits have a "rewritten" hint, try to show that in handles in other applications

Summary:
Ref T11522. This tries to reduce the cost of rewriting a repository by making handles smarter about rewritten commits.

When a handle references an unreachable commit, try to load a rewrite hint for the commit. If we find one, change the handle name to "OldHash > NewHash" to provide a strong hint that the commit was rewritten and that copy/pasting the old hash (say, to the CLI) won't work.

I think this…