Association display

[jrchudy]

This PR adds a BulkCreateForeignKeyObject object to ermrestJS that is attached to reference once the compute function is called to initialize the object.

I left a PR comment about prefillObject maybe being here instead of chaise and another one about composite keys.

Test cases added in this PR:

• table has 2 FKs + 3 columns that are NOT system columns
  • both FKs together are part of the same key
• table has 2 FKs that are NOT system columns
  • the FKs are no part of key information
• table has 3 FKs that are NOT system columns
• table has a composite foreign key from the association table to the main table
  • ensures this feature isn't triggered for composite FKs
• pure and binary association table

[jrchudy]

@RFSH This is ready for review now with the changes to chaise that are ready. We should discuss about the 2 comments I left in this PR about:

• how do we make sure the foreign key is not part of a composite foreign key
• should the prefillObject be a property of reference.bulkCreateForeignKey or stay as a state variable in chaise