Ensure that selected note is updated on launch when there are multiple updates

[mirka]

This fixes a syncing bug I found while looking into #825.

Steps to reproduce

1. After make dev, log in to the same account in both Electron and in a browser.
2. Pin a note to the top of the list.
3. Close the browser tab.
4. In Electron, make a change to the first line of the pinned note.
5. Make a change to the second note in the list.
6. Open the app in a browser tab.

The pinned note title is updated in the note list, but not in the editor.

Cause

This bug was introduced with the importer feature, where we started to debounce the noteUpdated action for performance reasons. This could then prevent the currently selected note from updating in the editor, if the update event was one of the calls dropped by the debounce.

Fix

Separate out the loadNotes call from the onNoteUpdate function, and only debounce the loadNotes call (contained in onNotesIndex).

[roundhill]