Misc fixes to sound module related to autodetect (#2669)•••* Sound options: don't immediately save changes when sound system gets autodetected; fix #2667
* If the config-saved sound system is not available anymore, force an autodetect; fix #2668
* Fix "qt" sound system under qt6 and unify the code path for Qt5.
* If phonon is available, prefer it over "qt" sound system (the latter can only play wav files)
* Nuke support for aRts (KDE2/3 sound server) and ESD (Gnome sound server before 2009)
* Sound module: replace SoundEffect with QmediaPlayer to support more file formats. Adjust the priority of "qt" sound system in autodetect
* Convert to smart pointers
* Sound options: force an autodetect if the current sound system is not valid