Address Arch Board feedback on DPG/ResponseClassifier APIs

[annelo-msft]

Arch board issue is here: Azure/azure-sdk#3979
API View is here: Azure.Core 1.23.0 APIView

• Determine whether we can avoid allocating CTS if we only have one CT (Yes, see Address Arch Board feedback on DPG/ResponseClassifier APIs #27357 (comment))
• Remove RequestOptions type: Remove RequestOptions from Azure.Core #27359
• Move AddClassifier methods to ResponseClassifier: Remove RequestOptions from Azure.Core #27359
• Rename CoreResponseClassifier -> StatusClassifier : Rename CoreResponseClassifier #27379
• Rename constructor parameter in CoreResponseClassifier to successStatusCodes: Rename CoreResponseClassifier #27379
• Change CoreResponseClassifier constructor to take ReadOnlySpan<ushort>: Fix bug blocking DPG and update CoreResponseClassifier constructor to take ReadOnlySpan<ushort> #27334
• Consider rename for ResponseClassificationHandler -> We will not rename this
• Resolve question regarding whether we need to add an async TryClassify in the 1.23.0 release

[annelo-msft]

Determine whether we can avoid allocating CTS if we only have one CT

Yes, we can: https://docs.microsoft.com/en-us/dotnet/api/system.threading.cancellationtoken.none?view=net-6.0#remarks

• "Two empty cancellation tokens are always equal."

Therefore we can compare CTs passed into HLC methods to CT.None to determine whether we have two CTs we need to link.