Drop the KF prefix for Qt6 builds, use Qt6 suffix instead
libkexiv2 is not a KDE Framework, so don't pretend to be one. Jumping on name change for Qt6 version anway, and going for
- library name: libKF5KExiv2.so.15.0.0 -> libKExiv2Qt6.so.0 (yes, SO version now just one number) (updated lib name)
- CMake config name: KF5KExiv2 -> KExiv2Qt6
- CMake target name: KF5::KExiv2 -> KExiv2Qt6
- include root path: include/KF5/KExiv2 -> include/KExiv2Qt6
MRs to adapt consumers:
Edited by Friedrich W. H. Kossebau