Required wait update stage and polling improvements

[cretz]

What was changed

• Created new WorkflowUpdateStartOptions as an extension of WorkflowUpdateOptions that has a required WaitForStage
• Created new WorkflowUpdateStage enum representing its proto equivalent
• Changed start update calls to require WorkflowUpdateStartOptions (:boom: breaking change)
• Disallow None or Admitted wait stage on start, user must specify one
• Updated start to continually start until stage reached or stage accepted, then poll if needed to reach complete
• Added test to confirm workflow and update completed in same task

Checklist

1. Closes [Feature Request] SDK clients should set a UpdateID on any update request even if the user did not specify one #198
2. Closes [Feature Request] SDK should not return an update handle if the update has not reached the desired state #199
3. Closes [Feature Request] Make StartUpdateAsync users aware that it's synchronous w/ worker.  #231

[Quinn-With-Two-Ns]

Could just allow the server to reject this call? That way you don't need to update the SDK if the server adds support .

[cretz]

Same thing was mentioned at temporalio/sdk-python#521 (comment). I think we need to document what works and what doesn't here anyways, so that'll have to be updated anyways, and hopefully this becomes a default parameter in some durable-update future.