VertexProgram Fails to Persist Multiproperties (FulgoraGraphComputer)

When setting a multiproperty in the execute() method of a `VertexProgram`, it updates an `ArrayList` with new values of the property. This `ArrayList` is supposed to be iterated over when persisting results to the graph in` FulgoraGraphComputer.submit()`. However, when performing a persist to the original graph (`ResultGraph.ORIGINAL`), it attempts to write the `ArrayList` as a single property, which fails since JanusGraph does not provide a default `ArrayList` serializer. I have code demonstrating this bug in https://github.com/bgamer50/janusgraph-test.

The fix for this is to check if an `ArrayList` is being written, and if so, write each individual value using `forEach()` using the predefined JanusGraph schema (either `Cardinality.LIST` or `Cardinality.SET`). If the JanusGraph schema was not defined as one of those two, throw an Exception. I have code for this fix in https://github.com/bgamer50/janusgraph-ab/tree/fix-vp-persist (`FulgoraGraphComputer` class).

Start in FulgoraGraphComputer.submit(), focusing on persistence for ResultGraph.ORIGINAL, and reproduce the multiproperty case with the linked janusgraph-test project. Compare the linked fix-vp-persist implementation and verify that persistence follows the predefined Cardinality.LIST or Cardinality.SET schema while rejecting other cardinalities.

Written by the indexing model from the issue text.