R1:dcc69977932b

Modernize "users" typeahead datasource

Summary: Ref T4420. Modernize users.

Test Plan:
- Edited "Commit Authors" on Audit search.
- Edited "Created By" on calendar search.
- Edited "invited" on calendar search.
- Edited "To" on "New conpherence message".
- Edited user on "Add user to conpherence thread".
- Edited "Authors" on countdown search.
- Edited "Author" on differential search.
- Edited "Responsible users" on differential search.
- Edited "Owner" on Diffusion lint search.
- Edited "include users"…