Desktop: Fixes #9699: Beta editor: Fix o not working in Vim normal mode

[personalizedrefrigerator]

Summary

Fixes the o command in Joplin's CodeMirror 6 Vim emulation.

o should open a new line and enter insert mode. It was failing because our CodeMirror5 version of this command tried to use codemirror.commands.vimInsertListElement, which wasn't registered for CodeMirror5Emulation.

Fixes #9699.

Testing

1. Enable the beta editor
2. Enable Vim emulation
3. Click on a non-list line
4. Press o
   • A new line should be opened after the current, the editor should be in insert mode
5. Type something, then press Escape
6. Click on a line in a list
7. Press o
   • A new line should be opened and the list should be continued.
8. Repeat steps 2-8 for the legacy CM5 editor.

This has been successfully tested on Ubuntu 23.10.