[FEATURE] Auto-render and attach HeaderAssets and FooterAssets

This patch adds a new method on ActionController,
initializeAssetsForRequest($request) which comes
with a default implementation and allows overriding
in subclasses.

The default implementation of this new feature will
try to render sections HeaderAssets and FooterAssets
from the Fluid template that is resolved, assigning
the output (if not empty) to either header or footer,
by using the PageRenderer.

The feature only works for TemplateView and
subclasses thereof, since `renderSection` is not a
required method for ViewInterface implementations;
it only exists on the (MVC-centric) TemplateView.

Change-Id: Ia815410637982c077236e12a848bdd26ead22e69
Releases: master
Resolves: #79409
Reviewed-on: https://review.typo3.org/51380


Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>