Update for Plasma 6.0.2
Note that everything behind the new DISTRO_FEATURE "desktop-portal" is not yet working correctly due to a couple of upstream topics:
- webengine is missing RISCV support in packaging
- appstream currently misses configuration options for qt API
- Meson upstream has issues with finding Qt native exes in libexec
Since those are already existing features, the MR is an improvement anyway.