Refresh backlinks regardless of whether editor content is stale

[bfollington]

Fixes #857

Changes

• Backlinks are now loaded independently of the memo in both the viewer and editor
• Backlinks are refreshed regardless of whether the editor content is refresh on .appear
• DataService.readMemoDetail and DataService.readEditorMemoDetail are both much simpler due to the introduction of DataService.readMemoBacklinks
• Both the viewer an editor will refresh backlinks and transcludes (in the case of the viewer) if indexing completes in the BG
  • To accomplish this I had to pass app down to the viewer and editor so they can replay select actions
  • I'd already done this on the profile, so I refactored into a common .fromAppAction pattern

[bfollington]

After chatting to @gordonbrander we think it's more sensible to hold off merging this and split apart backlink refresh from editor content refresh.

[gordonbrander]

A couple notes

[gordonbrander]

Direction looks good to me, but I have a few requests.

[gordonbrander]

Since this struct only carries an entry now, should we just respond with a MemoEntry?

[bfollington]

I think we still want to attach saveState here, so the struct makes sense?

[gordonbrander]

Oops, missed that. You're right.

[bfollington]

Address must be set on model to fetch backlinks as early as possible.

[gordonbrander]

LGTM

Would suggest playtesting since this touches the editor:

• Creating a note
• Deleting a note
• Renaming a note
• Creating a new note A, linking off to another new note B from it, following link to create B... does A show up in the related notes section?
• Opening the same note multiple times, changing the top one, paging back to the lower one. What happens?