Don't return update handles until desired stage reached

[Sushisource]

What was changed

• Add admitted stage to wait policy
• Don't return update handle from startUpdate until the update is complete if the user specified that stage (not sure why they would, though, when using start)
• Retry submitting update to server until seen accepted

Why?

See https://github.com/temporalio/features/issues/432

Checklist

1. Closes https://github.com/temporalio/sdk-java/issues/2002

2. How was this tested: Existing / new tests

3. Any docs updates needed?

[Quinn-With-Two-Ns]

While we are refactoring this area could we also do https://github.com/temporalio/sdk-java/issues/2045? I believe @cretz did this in python by requiring a wait stage be passed? If not I'll do it in a follow up PR.

[Quinn-With-Two-Ns]

Don't we also need to update the test server to return the updates current lifecycle state? or does the test server never actually return an empty response?

[Sushisource]

Don't we also need to update the test server to return the updates current lifecycle state? or does the test server never actually return an empty response?

I have changed it to do so - here for example https://github.com/temporalio/sdk-java/pull/2066/files#diff-809c076b3ee441df02cf0c4566a20f7abc69c94c15d8b689875350ae3fcdbfd9R1808