[TASK] Remove bower and update Gruntfile.js

Resolves: #81459
Releases: master, 8.7
Change-Id: I213c8d52d8c5ed0d027c1c6e7d01e9bec49ce506
Reviewed-on: https://review.typo3.org/53089


Reviewed-by: Markus Sommer <markussom@posteo.de>
Tested-by: Markus Sommer <markussom@posteo.de>
Reviewed-by: Johannes Goslar <jogo@kronberger-spiele.de>
Tested-by: Johannes Goslar <jogo@kronberger-spiele.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>