Update testing framework
Created by: dalg24
Following up on https://github.com/arborx/ArborX/issues/295#issuecomment-625326270
Scope creeped quite a bit...
List of changes:
- Upgrade OpenMPI to v4
- Allow non-CUDA enable MPI with CUDA build
- Import gpg keys from local server
- Update clang to v10
- Add
OMP_NUM_THREADS
andMPI_MAX_NUMPROCS
in testing - Replace one CUDA 10.1 build by 10.2
- Reorganize backends distribution among builds