Add driver extraction and compilation to our CI

[hiker]

With driver extraction started to be used in earnest, it would be great to include tests into our (internal) CI. Required work:

• Install BAF (https://github.com/MetOffice/lfric-baf)
  • Install the Fab version included in BAF, required to ensure we have matching features
• Compile one (small) apps with driver extraction (short time step would be ok). Skeleton, gravity_wave, Gungho should all be possible (lfric_atm kernel extraction still fails in various UM routines)
  • This will create driver*.F90 files (around 1600 for gungho)
• Run this small App
  • This will create netcdf output files for each executes kernel (around 440 for gungho)
• Compile all drivers
  • A few are known to fail at this stage
• Run all drivers for which we have a netcdf file.
  • And this involves parsing the numerical difference output table