Mobile: Fixes #9532: Fix cursor location on opening the editor and attachments inserted in wrong location

[personalizedrefrigerator]

Summary

Fixes two regressions:

• The editor cursor location was not preserved when closing/re-opening the editor. (Fixes Mobile: Editor cursor location not preserved when switching between the editor and viewer. #9532)
• Attachments were not inserted in the correct location. (Fixes iOS: Drawings and attachments always added to end of note #9509)

The underlying cause was a type-related issue that caused the selection to not actually be saved (saving undefined instead).

Note

This is a version of #9533, rebased on release-2.13.

Testing

1. Create a new note with a large amount of content
2. Scroll to the middle of the note
3. Attach a drawing
4. Close and re-open the editor

After step 4, the editor should be scrolled to roughly its original location and the drawing should be attached where the cursor was previously.

This has been tested on an Android 7 device.

A previous version of this pull request (based on dev) was tested on an iOS 17 device.