[BUGFIX] RTE: Status bar update is happening too late

Force status bar update on initialization and before each toolbar update.

Releases: master
Resolves: #63970
Change-Id: I39833e1256b9b5df2ad0400238278d59921f00c0
Reviewed-on: http://review.typo3.org/35556
Reviewed-by: Stanislas Rolland <typo3@sjbr.ca>
Tested-by: Stanislas Rolland <typo3@sjbr.ca>