The minimum CMake version for Qt6 is 3.16, so all the calls to
cmake_minimum_required() are updated here to enforce that
minimum. This will avoid any CMake version-related warnings
from Qt.
Avoid hard-coding Qt5 where the tests could now be using
Qt5 or Qt6.
Fixes: #22188
This test case enables AUTOMOC on the same sources in two separate targets.
This causes the `moc_*.cpp` generation custom commands to be added to multiple
`_autogen` targets, which is not allowed by the Xcode "new build system".
Skip the part of the test that triggers this problem for now.
Issue: #21205
Some AUTOGEN tests require the Qt core libraries only and
some require the Qt gui libraries to function.
This replaces the AutogenTest.cmake script with two specific
AutogenCoreTest.cmake and AutogenGuiTest.cmake scripts that
are included on demand.
Craig Scott