Refine global search UI for tokenizer functions

Summary:
Ref T4100.

• Removes the "with unowned" checkbox in favor of the "no owners" function.
• Support functions in "Authors" and "Owners".

Test Plan:

• Ran various global search and Maniphest queries.

{F379931}

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T4100

Differential Revision: https://secure.phabricator.com/D12523