[TASK] RTE: Migrate the editor toolbar to plain JavaScript

The toolbar container is plain JavaScript but the buttons, combos and
other widgets are still ExtJS objects.

Releases: master
Resolves: #63794
Change-Id: Ib88431a1c1463f75fc05ec12c5a30d274dc2212a
Reviewed-on: http://review.typo3.org/35487
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>