Add support for x-ms-long-running-operation-options.final-state-schema

[mikekistler]

Autorest has added a new field to the x-ms-long-running-operation-options specification extension, final-state-schema.

https://github.com/Azure/autorest/tree/main/docs/extensions#x-ms-long-running-operation-options

final-state-schema can be used to point to the definition of the response schema returned from the final-state-via. Previously this schema was specified on the 200 response for the operation, but this was problematic because the operation may not actually return 200. final-state-schema allows the API author to avoid "fibbing" about the 200 response just to make autorest work.

aaz-dev-tools should also add support for final-state-schema.