Making this simply depend on Qt5 or Qt6 was short-sighted as work on QtLocation
upstream continues. Instead break this out as its own option.
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
There was always this weird asymmetry that the "maintab" widget
is one of the tabs itself, whereas the additional tabs were
treated as extra-widgets. Turn the first tab into explicit
source files to make the distinction between container and
content clear.
Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>