R1:94a95efa059a

Replace "loadUnsubmittedInlineComments()" with a modern "DiffQuery"

Summary: Ref T13513. All queries now go through a reasonably minimal set of pathways and should have consistent behavior.

Test Plan:
- Loaded a revision with inlines.
- Created a new empty inline, reloaded page, saw it vanish.
- Created a new empty inline, typed draft text, did not save, reloaded page, saw draft present.
- Created a new empty inline, typed draft text. Submitted feedback, got prompt, answered "Y", saw draft text submit.