Provides a way for users to actually delte their user drafts where
required.
For #3927
Added test to cover new endpoint.
Makes update to MD editor #setText so that new selection is within new
range, otherwise it errors and fails operation.
- Tweaked styling to add a little extra shadow and be more rounded to
match other UI areas.
- Added slight horizontal inset when in right sidebar to prevent shadow
being cut-off in most cases.
- Added logic to "drop upwards" if dropping down would take the menu
offscreen.
- Updated all dropdown list item actions into three specific styles:
icon-item, text-item & label-item. Allows a stronger structure while
prevents mixing of styles as we were getting for header dropdown in
dark mode.
- Extracted out page editor top toolbar to its own view file & split
editor switch options to different markdown options.
