Add Windows CI build

[olemke]

This PR adds an initial Windows CI build using the Microsoft C++ compiler.

To improve build times, the default build system is now Ninja. If you prefer the old way, you can switch back to makefiles by passing the -G option during the cmake configure stage, e.g.:

cmake --preset=default-clang-conda -G "Unix Makefiles"

Ninja is installable through conda.

Current Windows caveats:

• no Fortran support, i.e. no Fastem, no RT4, no Tmatrix
• no Disort
• no MT CKD continua
• no OpenMP support
• no GUI support