[TASK] Replace favicon with autosizing variant

Replaces the favicon by a autosizing variant including
16px, 32px, 48px and 64px resolutions.

Resolves: #70080
Releases: master
Change-Id: Ic18ecceeffec8905dc734399b3979dc4198f5ac6
Reviewed-on: http://review.typo3.org/43524


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>