R1:5645a07d9984

Modernize DifferentialInlineCommentQuery

Summary:
Ref T7447. This class is currently a big mess with a lot of `withWeirdSpecialThingUsedInOnePlace()` type qualifiers.

Try to generalize/normalize it a bit.

Test Plan:
- Viewed inline comments.
- Created a new inline comment.
- Edited an inline comment.
- Marked an inline comment complete.
- Deleted, then undeleted an inline comment.
- Previewed inline comments.
- Viewed drafts as another user, verified they don't show up.

Reviewers: btrahan

Reviewed By…