collaboration capable workflow - first pass

[mwdchang]

Summary

Version 0 of workflow collaboration feature. Not we assume that people will not modify the same exact node at the same time.

• The changes add/augment the Java classes for WorkflowNode and WorkflowEdge, adding in version number and isDeleted tombstone flag. Note currently this is only for API end - the UI side is still using their own types. Consolidation will come later.

• Add in logic to handle entire-workflow update, this introduces tombstoning logic, meaning that we do not delete nodes/edges, but rather just mark them as deleted.

• Update UI workflow service to account for tombstoning

Testing

You need two terarium browser sessions, A and B

• A: create workflow, add model operation, add model-config operation, connect them
• B: goto the same workflow, verify you can see model => model-config
• A: add another operation, say simulate, wait for 7-8 seconds for workflow write to occur or check network tab for workflow-POST
• B: remove the model operation, wait for 7-8 seconds for workflow write to occur or check network tab for workflow-POST
• A: refresh, verify that we still have simulated operation, verify that model-operation is removed
• B: refresh, verify that model operation is deleted, plus that there is a new simulate operation

[jryu01]

LGTM