feat: Add kernel build options

[victorapm]

This PR introduces build options for the generated (templated) kernels. All kernels are turned on by default, as in develop, and they can be switched off to produce simpler and faster builds. For example, on a 16-cores workstation:

Develop:

$ cmake 2>&1 | grep 'Total number of generated kernels'

-- Total number of generated kernels: 518

$ time make -j16 geosx > /dev/null 2>&1

real	14m45.726s
user	185m47.633s
sys	4m56.323s

This branch (Only elastic solidmechanics + isothermal flow):

$ cmake -DGEOS_ENABLE_FLUIDFLOW_THERMAL_FVM=OFF -DGEOS_ENABLE_FLUIDFLOW_REACTIVE=OFF -DGEOS_ENABLE_FLUIDFLOW_HYBRIDFVM=OFF -DGEOS_ENABLE_MULTIPHYSICS_POROMECHANICS_EFEM=OFF -DGEOS_ENABLE_MULTIPHYSICS_POROMECHANICS=OFF -DGEOS_ENABLE_MULTIPHYSICS_POROMECHANICS_DAMAGE=OFF -DGEOS_ENABLE_MULTIPHYSICS_THERMOPOROMECHANICS=OFF -DGEOS_ENABLE_SOLIDMECHANICS_EXTRA=OFF -DGEOS_ENABLE_SOLIDMECHANICS_THERMOPOROMECHANICS=OFF 2>&1 | grep 'Total number of generated kernels'

-- Total number of generated kernels: 49

$ time make -j16 geosx > /dev/null 2>&1

real	10m47.826s
user	92m11.497s
sys	2m21.608s