Autotools: Replace --with-qt5 / --with-qt6 with --with-qtver=(qt5/qt6)
Attached patches add the new --with-qtver option, and deprecate old --with-qt5 / --with-qt6 but does not yet completely remove them.
New patch versions that improve deprecation warning.
To make it possible to pass similar configure parameters to both S3_1 and master, replace configure options --with-qt5 (master) and --with-qt6 (S3_1) by uniform --with-qtver=(qt5/qt6). Only the default value, when the option has not been given at all, needs to differ between the branches.