[TASK] Remove old prototype.js utilities

One of the initial JS files with prototype
called common.js (which was moved from
typo3/js/common.js into EXT:backend
with the file structure change) was previously
used for calls using Prototype AJAX
calls.

The file was now used in two areas:
- backend.php - containing an instance of
the mother object "TYPO3" used for the
backend scaffolding via ExtJS.
- old Prototype trees (loaded in DocumentTemplate)
introducing an API when using prototype as AJAX handler
when errors from AJAX requests occurred (was piped
to the ExtJS debug bar).

Removing the common.js file leads to
a) moving the "mother object" TYPO3 into backend.js
where all other ExtJS initialization for the TYPO3 Backend
is done.
b) "old" Trees using AJAX without the hook
for show error messages.

The toolbarmanager.js file was a base
helper function to open/hide toolbar items
which is now completely provided with
Bootstrap's dropdown functionality.

As a result, the prototype/scriptaculous
component is not needed in backend.php
anymore, and is removed by default.

Any extension that needs prototype in the
backend.php namespace can of course
re-enable scriptaculous.

Resolves: #62926
Releases: master
Change-Id: Icbbc048944360c3ac469c816ad07c4a2a112836b
Reviewed-on: http://review.typo3.org/34098
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Felix Kopp <felix-source@phorax.com>
Tested-by: Felix Kopp <felix-source@phorax.com>