There have been a lot of changes to the identity service proto file since we last ran the codegen for grpc-web.

I ran the codegen again and spent ~1 hr with @varun patching up the Flow types.

Depends on D9491

1. Set up prereqs following instructions here
2. Run local identity service following instructions here
3. I used this patch to test: https://gist.github.com/Ashoat/7cf4a0fbdebc152d585884184bc0ac07