[BUGFIX] #62145 fix urls for BE functions

The functions inside the TYPO3 Backend module do not work
since update to 6.2 on SSL enabled Backends.

* Remove the hardcoded links to index.php
* Use getModuleUrl api instead of building the link
  manually in linkSelf

Fixes: #62145
Change-Id: Ic650060e367fef2399e50e3ae826ffb683bf6648
Reviewed-on: http://review.typo3.org/33819
Reviewed-by: Dmitry Dulepov <dmitry.dulepov@gmail.com>
Tested-by: Dmitry Dulepov <dmitry.dulepov@gmail.com>