[Bug] Handle possibility of update-before-start

[Sushisource]

Describe the bug

Because of the fact that we re-order updates to come before other things a-la signals in Core, it's currently possible to handle an update before running the first bit of workflow code if an update comes in same task as start workflow.

We'll likely need to buffer things as we do in other SDKs (in lieu of making some other choice)

Minimal Reproduction

See the test_workflow_update_handlers_unhappy test and discussion here

Environment/Versions

• OS and processor: [e.g. M1 Mac, x86 Windows, Linux]
• Temporal Version: [e.g. 1.14.0?] and/or SDK version
• Are you using Docker or Kubernetes or building Temporal from source?

Additional context