Standardize MLFlow spatial_cc and qm9_cc

[audiracmichelle]

[audiracmichelle]

process_qm9_dataset becomes unnecessary when the existence of the datapath is tracked my InMemoryDataset

[audiracmichelle]

lifter and Combinatorial Complex defined in lift_qm9_to_cc should be incorporated into QM9_CC object

[audiracmichelle]

change CombinatorialComplexData().from_json() to CombinatorialComplexData.from_ccdict()