Add architecture information to qtpaths -query output

The Qt vscode extension uses the qtpaths -query output to generate kits. Sometimes architecture information is needed for example the target architecture for cross-compilation. We parse qt.conf and `modules/Core.json` in the current extension implementation. Instead of doing that, we can add version info to qtpaths -query.

Possible -query output

...
QT_ARCH: x86_64
or 
QT_HOST_ARCH: x86_64
QT_TARGET_ARCH:arm64
...