Add UM7 rigorous build option

[MartinDix]

To enable bounds checking and NaN initialisation, https://github.com/ACCESS-NRI/UM7/issues/37

Compiler options -fp-model strict -check all -check noarg_temp_created -init=snan -init=array -init=huge based on those used in current UM, https://code.metoffice.gov.uk/trac/um/browser/main/trunk/fcm-make/nci-x86-ifort/um-atmos-rigorous.cfg

Overrides to turn some checks off for instances of deliberate 1D overindexing etc.

[manodeep]

@MartinDix Do these memory sanitizers require all dependencies to be built with those memory sanitizer flags as well?

Possibly relevant: https://community.intel.com/t5/Intel-Fortran-Compiler/IFX-issue-when-building-check-all-or-check-uninit/td-p/1545825

[MartinDix]

This is a problem with ifx but wasn't with ifort. The model fails with an immediate error.

With ifx I've used -check noinit. The NaN initialisation is still useful because it'll eventually show there's a problem. It's just going to be harder to locate it.