[BUGFIX] Change tooltip for page tree area toggle button

This patch adds a new tooltip to the button to toggle the tree area.
It also chenges the tooltip for the drag area, because the action did
not affact the "tree" itself but the "tree area".

Resolves: #66037
Releases: master
Change-Id: I196edd5cef14bb9bb10f87412914537ddb787b9f
Reviewed-on: http://review.typo3.org/38226


Reviewed-by: Cedric Ziel <cedric@cedric-ziel.com>
Reviewed-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Tested-by: Mathias Schreiber <mathias.schreiber@wmdb.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>