WIP: Add support for PCH

TODOs:

• Should we add PCH support at all?
• Decide whether we want to turn nbnxm into module If so fix OpenCL and CUDA
• Should we have an interface libary to share the PCH settings between modules
• Do our modules have the exact same compiler flags and can we resuse the PCH artefact?
• Is the selection of what's in the PCH ok?
• Add required conditionals for cmake<3.16
• Do we want this only in master?

Results (for Debug build on i7-9700KF):

• Total build time from ~380s to 70s
• Parse time from 728s to 137s