All the actual code of the module was subject to #ifndef QT_NO_DOM,
aside from the *_p.h that were only included subject to such #if-ery,
so there's nothing left of the module if the feature is ever disabled,
but be consistent with the module defining a feature that allows that.
Convert #ifndef QT_NO_DOM to #if QT_CONFIG(dom) (and move to outside
the namespace, where nothing was inside without the define), require
feature dom in the *_p.h and test, change CMake config to skip the
test when the feature is disabled (and add a missing SPDX comment),
condition including sources on the feature.
Pick-to: 6.7 6.5
Task-number: QTBUG-122619
Change-Id: Ie2167b6c56d96c7804785e225f3fe02dbc78984c
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
(cherry picked from commit a4c85a5cf19d8919797aba41077bfa8796427f54)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
e5c551a5cf