[FEATURE] Add Backend Preview to ContentObject
Adding an additional Template for the ContentObject to preview the values in the Backend.
If a ContentObject Template already exists no additional Backend Template will created.

Resolves: #62738
Change-Id: I7bd52d195c3e1f7b2feea57c11d10d8e2c55f4aa
Reviewed-on: http://review.typo3.org/34309
Reviewed-by: Tim Lochmüller <tim@fruit-lab.de>
Tested-by: Tim Lochmüller <tim@fruit-lab.de>