Generalized AtomsToData class

[emsunshine]

Recent changes and discussions (such as #492, #513, and #520) have highlighted the need for a generalizable way to transform ASE atoms objects into torch_geometric Data objects. Such a class would effectively replace AtomsToGraphs.

It would be useful if this function was capable of including many different properties without adding tons of keyword arguments (the way AtomsToGraphs currently has r_energy, r_forces, r_pbc, etc.). It may even be possible to include arbitrary properties. Perhaps it could use the new metadata guesser in some way?

This functionality would reduce the entry barrier for people building models/trainers for properties other than officially supported ones (energy and forces). It would also be good from a code readability standpoint since, in practice, AtomsToGraphs is currently most often used for things other than turning atoms into graphs.

[github-actions]

This issue has been marked as stale because it has been open for 30 days with no activity.

[mshuaibii]

PR #622 now provides support for defining arbitrary properties that we want to get written into the data object (r_data_keys)