MACE-LAMMPS meta issue

[wcwitt]

I need a place to organize/triage some LAMMPS-related issues.

• [ ] better tests for different architectures!
• [ ] need to document multi-GPU https://github.com/ACEsuit/mace/discussions/274
• [ ] this PR needs merging https://github.com/ACEsuit/lammps/pull/1 (and related https://github.com/ACEsuit/mace/issues/195#issuecomment-1838942935)
• [ ] need to tidy/improve single-precision support for Kokkos https://github.com/ACEsuit/mace/discussions/274
• [ ] need per-atom energies in Kokkos mode https://github.com/ACEsuit/mace/issues/193
• [ ] a request for per-atom virials https://github.com/ACEsuit/mace/discussions/272
• [ ] investigate Kokkos::parallel_scan to tidy the Kokkos code (suggested by Anders Johansson)
• [ ] refactor the MPI splitting using something like MPI_COMM_WORLD_rank % n_gpus_per_node (suggested by @bernstei)
• [ ] request for plug-in mode (need to think about this one) https://github.com/ACEsuit/mace/issues/271
• [ ] problem compiling with MPI turned off (reported by Philip Pracht)

[ilyes319]

Excellent idea, thank you!