Consolidate hoomd writer workflow #887
Description
Describe the behavior you would like added to GMSO
Right now, the workflows in gmso.external.convert_hoomd involve 2 steps to 1) create a snapshot and 2) create the hoomd forces. This can be kind of awkward. There are flags (auto_scale, base_units, etc..) that have to defined twice, if the user isn't consistent in both cases, issues could arise.
Also, with #850 being close to merging, there are new things to think about. For example, if the topology contains rigid bodies, the snapshot writers will check and handle this, but there should also be some checks and new behavior in to_hoomd_forcefield such as updating neighbor list exclusions, setting non-interacting pairs between rigid body particles and other particles, etc..
All that is to say, the user experience, and maintainability of our Hoomd writers would be improved if we consolidate these steps
Describe the solution you'd like
I imagine a single wrapper method that returns everything.
snapshot, forces, ref_units, rigid_obj = to_hoomd_simulation(...)
where to_hoomd_simulation calls the existing to_gsd_snapshot and to_hoomd_forcefield under the hood. We should probably rename these methods so that they are "hidden".