Refreshing visibility of QS elements whenever configuration changes

Previously visibility was refreshed only when rotation happened but we want to handle other cases as well, e.g. switching screens.
Also unifying refreshVisibility methods for both footer and brightness slider.

Fixes: 195922194
Test: manual
Change-Id: I05a8ac29df117a0d7b2e6df22ccd62cea80bb12b
4 files changed