[TASK] Pagetrees: adopt open/close icons and align items of same level

[TASK] Pagetrees: adopt open/close icons and align items of same level

Adopt open/close icons for pagetrees (except for the main TYPO3 pagetree).
Fix width of last-child li's before-pseudo-element. Slightly adjust the
left padding for the filelist navigation frame. Introduce new open/close icons
for module configuration and module template "TS Object Browser".

Resolves: #68649
Related: #68507
Releases: master
Change-Id: I4d8edf7345ca77e1f36426ed90e975df5016cc0c
Reviewed-on: http://review.typo3.org/42145
Reviewed-by: Benjamin Kott <info@bk2k.info>
Tested-by: Benjamin Kott <info@bk2k.info>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>