newapkbuild: build debug symbols with meson and CMake
We currently use the 'Release' buildtype for both of these, which produces and optimized build, without usable debug symbols. By switching to 'debugoptimized' in meson and 'RelWithDebInfo' in CMake we can keep optimized builds but also get useful debug symbols.
CC @PureTryOut since you've been introducing this for the majority of KDE packages already AFAICS.