Trigger Fortran Pre-Processor by file-suffix .F90

Since all compilers in use understand the .F90 pre-fix to trigger pre-processing, we can drop setting the pre-proc compile flag by hand. This also enables using the Ninja generator.

Also, the gcov compiler flags have been updated, since it was not linking against lgcov: https://gcc.gnu.org/onlinedocs/gcc/Instrumentation-Options.html

HPC module load scripts have been updated to v1.4

CI: Coverage stage fixed