Editor error message misleading due to re-used key. (#29859) (#29876)

Editor error message misleading due to re-used key. (#29859) (#29876)

Backport #29859 by @buckybytes

The error message:

`editor.file_changed_while_editing = The file contents have changed
since you started editing. <a target="_blank" rel="noopener noreferrer"
href="%s">Click here</a> to see them or <strong>Commit Changes
again</strong> to overwrite them.`

Is re-used in inappropriate contexts. The link in the key goes to a 404
when the key is used in a situation where the file contents have not
changed.

Added two new keys to differentiate commit id mismatch and push out of
date conditions.

Co-authored-by: buckybytes <158571971+buckybytes@users.noreply.github.com>