[CLEANUP] Page Module: Do hovering via CSS, not JS

The ExtJS functionality for adding active classes can
be done via CSS hover pseudo classes.

This is faster (native browser functionality) and
also removes some ExtJS code. With this change
however, the hovering is not disabled
anymore when dragging.

Releases: 6.2
Resolves: #58359
Change-Id: Ifcc0307b436cf68dfcfe561444e779410978d576
Reviewed-on: https://review.typo3.org/29744
Tested-by: Stefan Neufeind
Reviewed-by: Nadir S.
Tested-by: Nadir S.
Reviewed-by: Nico Schober
Tested-by: Nico Schober
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Nicole Cordes
Tested-by: Nicole Cordes