Remove trigger type for workflows

[antho1404]

The trigger now has 2 fields

• taskKey
• eventKey
  instead of a generic key (that was confusing with the nodeKey).
  The proto definition now uses a oneof for this.

I also changed the scheduler to have two functions for processEvent and processResult this creates a bit of duplication but makes it much easier.

TEST:

You can still take the services dataset from #1209
but the workflows need to be updated with:

// event
{"key":"event","trigger":{"instanceHash":"EKaTkkmNpAJeikEMvSTNNZeM6et7kS9iyU77QrAPAMqx","eventKey":"eventX","nodeKey":"task1"},"nodes":[{"key":"task1","instanceHash":"CVyX2UwCSiCvmUEybXw6cu4ABSoHbDVgTyvx8UgXXP7B","taskKey":"taskY"},{"key":"task2","instanceHash":"FXGpKzcEHMnyr2BQrH44Dq2SoAYtjw1C7qNRVGbxTNpa","taskKey":"taskZ"}],"edges":[{"src":"task1","dst":"task2"}]}

// result
{"key":"result","trigger":{"instanceHash":"EKaTkkmNpAJeikEMvSTNNZeM6et7kS9iyU77QrAPAMqx","taskKey":"taskX","nodeKey":"task1"},"nodes":[{"key":"task1","instanceHash":"CVyX2UwCSiCvmUEybXw6cu4ABSoHbDVgTyvx8UgXXP7B","taskKey":"taskY"},{"key":"task2","instanceHash":"FXGpKzcEHMnyr2BQrH44Dq2SoAYtjw1C7qNRVGbxTNpa","taskKey":"taskZ"}],"edges":[{"src":"task1","dst":"task2"}]}

// result from other workflow
{"key":"result-from-other-workflow","trigger":{"instanceHash":"CVyX2UwCSiCvmUEybXw6cu4ABSoHbDVgTyvx8UgXXP7B","taskKey":"taskY","nodeKey":"task1"},"nodes":[{"key":"task1","instanceHash":"FXGpKzcEHMnyr2BQrH44Dq2SoAYtjw1C7qNRVGbxTNpa","taskKey":"taskZ"}],"edges":[]}