Heads up about cmake plans

Seems like upstream CMake has plans to make our life easier:
https://discourse.cmake.org/t/how-to-control-the-location-of-the-c-20-binary-module-interface-bmi-output-directory/7968/18?u=lecris

Basically there will be a custom target to build all build-time dependency files. This is related to supporting `clang-tidy` and cxx-modules