Philippe 18/09/2023: FLAT_INV: fix for NOOPENACC (deallocate ZBAND_YT and ZBAND_YRT only if allocated)

Philippe 12/09/2023: remove key MNH_PGI (not useful anymore, was to workaround an bug in very old version of PGI compiler)

(cherry picked from commit a7413073)

Philippe 29/08/2023: OpenACC: work around for a problem with NVHPC 23.7 (not present in older versions)

(cherry picked from commit ce39d7dc)

Philippe 29/08/2023: OpenACC: work around for a problem with NVHPC 23.7 (not present in older versions)

Juan 25/07/2023:ZSOLVER/advection_metsv.f90 , add cpp key MPIVIDE to compile with gfortran+GPU nvidia or amd

Philippe 25/07/2023: transfer ZSOLVER/ppm.f90 to MNH/ + adapt it. This gives better performance on GPUs.

Philippe 17/07/2023: FFT: invert loops for better performance and to allow correct parallelization by NVHPC OpenACC

Philippe 26/06/2023: ice4_sedimentation_split: remove a DO CONCURRENT because of a reduction in loop (wrong reults with NVHPC 23.5)

(cherry picked from commit ad799fd0)

(cherry picked from commit 18a466fd)

Philippe 26/06/2023: ice4_sedimentation_split: remove a DO CONCURRENT because of a reduction in loop (wrong reults with NVHPC 23.5)

(cherry picked from commit 9c064dd7)

# Conflicts:
#	src/MNH/advection_metsv.f90
#	src/MNH/advection_uvw.f90
#	src/MNH/ice4_fast_rg.f90
#	src/MNH/turb.f90
#	src/ZSOLVER/advection_uvw_cen.f90
#	src/ZSOLVER/dyn_sources.f90
#	src/ZSOLVER/gdiv.f90
#	src/ZSOLVER/get_halo.f90
#	src/ZSOLVER/pressurez.f90
#	src/ZSOLVER/rain_ice_red.f90
#	src/ZSOLVER/turb.f90

Juan 19/06/2023:rain_ice_sedimentation_split.f90, Again SegFault at execition with CRAY ftn -> deactivate mnh_expand_array for CRAY ftn !!!

Juan 19/06/2023:rain_ice_sedimentation_split.f90, For pref PB with nvhpc , reintroduce mnh_expand_array & MNH_MEM_GET(ZRTMIN...) + replace data create -> present

Juan 16/06/2023:ZSOLVER/* , For Nvhpc , remove duplicate "!$acc loop" introduced by use of mnh_do_conncurrent

Juan 16/06/2023:ZSOLVER/pressurez.f90 , For CRAY ftn ,transform  mnh_do_concurrent -> DO CONCURRENNT to avoid serialisation of BR_ call

Juan 16/06/2023:MNH/* , For Nvhpc , remove duplicate "!$acc loop" introduced by use of mnh_do_conncurrent

Juan 16/06/2023:rain_ice_sedimentation_split.f90, Strange Cray SegFault -> replace mnh_do_concurrent -> array syntax

Juan 15/06/2023:ZSOLVER/turb.f90, For gfortran+openacc doesnt allo EXIT on acc loop -> replace with GZD logical test