Adds the bind `ui_text_remove_secondary_carets` to TextEdit, with ESC as the default shortcut.
When the bind is performed, if the TextEdit has multiple carets, `remove_secondary_carets` is called and secondary carets are removed.
This is useful when multiple selects are performed with `add_select_for_next_occurrence` #67644 or when multiple multiple carets are manually added, then it's possible to go back to a single caret with a shortcut.
Closes#67991
fcff978763