Make AlchemiscaleClient.get_transformation_chemicalsystems return a tuple, ordered by (<state>)

[dotsdl]

Currently, calling AlchemiscaleClient.get_transformation_chemicalsystems yields the ScopedKeys for the ChemicalSystems associated with the given Transformation, but in a list in random order. This method would be more useful if it returned instead a tuple giving the ScopedKeys for the ChemicalSystems in order based on the state these correspond to, e.g. stateA or stateB.

This could be accomplished in the Neo4jStore layer by making the query sort the resulting ScopedKeys by the value of the attribute property on the DEPENDS_ON relationship between the Transformation and its ChemicalSystems.