Use OperationInternal for CertificateOperation

[heaths]

I used OperationInternal for pseudo-LROs in Key Vault with PR #25593 (issue #22912) but CertificateOperation is a bit different and may require additional discussions and changes to OperationInternal (or OperationInternal<T>) to support cancelled states. Specifically, the Cancel and Delete methods on CertificateOperation need consideration whether that creates a successful state with no value or a failed state, which would cause subsequent UpdateStatus/Async calls to throw, which would be a behavioral change.

I don't think any of this is necessarily a hard problem to solve, but being shared code want to make sure we consider a robust strategy.

[pallavit]

@heaths - Is this still an issue we want to tackle?

[heaths]

Those working on our helpers like Pavel and @AlexanderSher back in the day requested this, but it's clearly not been a priority. Personally, I don't think it's worth it and, if we get serious about auto-generating, would be done automatically anyway. I wonder if Alexander still wants this?

[pallavit]

I will go ahead and close it in that case.