Add the ability to require a Qt version

[ahayzen-kdab]

In CxxQtBuilder or qt_build_utils it would be useful to be able to

• Require a Qt major version or minimum version eg 6.x or 6.2+
• Require an exact version such as 6.5.0

[ahayzen-kdab]

This is now possible using the semver::Version from QtInstallation with a semver::VersionReq::matches.

[ahayzen-kdab]

Instead this is about exposing the QtInstallation trait instance from the cxx-qt-build.