Mix commit notes with merge request notes on MR show page
Created by: riyad
general:
- add ids to diff lines (for linking, see below)
- add helpers for dealing with notes for different targets
on MR show page
- show merge request notes together with all the notes from its commits
- if a note is from a commit/diff line add a link to the commit/line
- fix vote counting to only count merge request notes (not commit notes)
Depends on #1629 Fixes #1622
screen shot:
