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.
• Created a new empty inline, typed draft text, scrolled down to bottom of page, typed non-draft text, saw preview include draft text.
• Marked and submitted "Done".
• Used hide/show on inlines, verified state persisted.
• Did much of the same stuff in Diffusion, where it all works the same way (except: there's no prompt when submitting draft is-editing inlines).

Maniphest Tasks: T13513

Differential Revision: https://secure.phabricator.com/D21234