Refactor hoomd.Snapshot.from_gsd_snapshot.
Refactor hoomd.Snapshot.from_gsd_snapshot.

Use a helper function to remove redundencies and decrease function size.

joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue,joaander/hoomd-blue