Quentin 05/02/2023: bf for merge MNH-55X-dev-OPENACC-FFT into 56-branch : need of modifs of gradient_m for computation outside of physics

Merge remote-tracking branch 'refs/remotes/origin/MNH-55X-dev-OPENACC-FFT' into MNH-55X-dev-OPENACC-FFT

(cherry picked from commit b20d4c81)

Philippe 13/12/2023: downgrade HDF5 from 1.14.3 to 1.14.2 to workaround a known bug (to be corrected in future version 1.14.4)

(cherry picked from commit e6926992)

(cherry picked from commit 8c43f306)

Philippe 01/02/2023: libaec: provide configure and other files in archive (instead of using autoreconf that is not available everywhere)

(cherry picked from commit e0a022dd)

(cherry picked from commit eff39592)

(cherry picked from commit d3c148fa)

(cherry picked from commit e14a400f)

(cherry picked from commit 2d8bbca4)

(cherry picked from commit b9f814ed)

(cherry picked from commit 1a59e431)

(cherry picked from commit 174d4eda)

(some missing data problems with OpenACC disappear maybe because less array copies)

Juan 13/12/2023:Rules.LXnvhpc2202.mk, Compile MultiGrid Halo on OPENACC only , for better performance on MPI routines

Juan 11/12/2024:condsamp.f90, PB Bitrepro -> replace SUM be SUM_DD_R2_ll & average on all interiors pts for NFINDTOP = 0 ou 2

Philippe 11/12/2023: OpenACC: contrav: add condition for data present for some variables (available or not depending on the condition)

(cherry picked from commit 4795ceda)

(cherry picked from commit 461e264e)

Juan 30/11/2023:Rules.LXarm.mk , Bug on parallel I/O due to mnh_expand , missing -DMNH=MNH, to generate/managed correctly MNH file type

Juan 29/11/2023:configure, For ADASTRA , managed OPTLEVEL=...DEFONLY CPU version -> dont load accel stuff