Expose UpdateID in an update handler

[drewhoskins-temporal]

This will allow users to use it when they want a unique idempotent primary key for handlers.

[roxblnfk]

Looks like we already have it https://github.com/temporalio/sdk-php/blob/cc879864a3fe0cf023d941b99f7c5e31f4c82ff7/src/Client/Update/UpdateHandle.php#L45-L48

[cretz]

I think that is for the client. This is for access inside the handler inside the workflow. Go is using context for this, other languages are using "async local" or similar. Unsure the best approach in PHP for providing contextual state to a handler (and things it may start) without affecting anything outside the handler.

[roxblnfk]

This is for access inside the handler inside the workflow

Got it. Thanks.