Document how to work with CMake projects

There doesn't seem to be any documentation for how to work with CMake projects.

Example: if I wanted to know how to select the Qt version for my CMake project, I'd look here https://doc-snapshots.qt.io/vstools-dev/qtvstools-how-to-select-qt-versions-for-project.html
But the content won't help me.

We should document

• how to load a Qt CMake project (even if this seems trivial)
• recommend Visual Studio settings such that CMake preset files are preferred
• what preset files are created with a short overview of their Qt-specific content
• how to work with these files (for example, how to change the used Qt version in CMakeUserPresets.json)