Make details view mode's full row activation optional

In d3839617

 the details view mode
was changed in a way that made the full row of an item the click
target instead of only having the item's icon and text be the
representative clickable area of an item.

This commit makes this new behaviour optional through a setting
which can be changed in Dolphin's settings dialog.

The explanation for introducing yet another setting in this case is
as follows:

While the introduced change is an improvement for many typical
workflows, there are some workflows for which this new behaviour
is problematic. Quite prominently a usage of Dolphin that tries
to maximise information density is made worse by the change because
now side padding is necessary to click the view's background. While
the side padding is and was optional, disabling it made switching
the active view in split view mode more difficult among other
things. For a more complete discussion about the issues, please
check out the bug report(s) and the discussion in Dolphin's gitlab
issue with number 34.

Co-authored-by: Ivan Čukić <ivan.cukic@kde.org>

BUG: 453700
FIXED-IN: 22.12