Generate a tsp-location file as part of the openapi generation step

There is a need for various tools and validation steps to map back from a generated openapi document to the typespec that generated it. I would like to propose we generate a metadata file similar to what the sdk languages do with a tsp-location file (i.e. https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/openai/Azure.AI.OpenAI/tsp-location.yaml) that will contain a relative path to the TypeSpec that generated it.

This will enable us to give better errors from our validation tooling as well as to allow us to correlate an openapi APIView with its TypeSpec APIView.

I would suggest we do this for both the typespec-autorest and typespec-openapi3 emitters.

Start by locating the generation steps for the typespec-autorest and typespec-openapi3 emitters, then compare the proposed metadata with the linked SDK tsp-location.yaml example. Done means both emitters produce a tsp-location file containing a relative path to the TypeSpec source that generated the OpenAPI document.

Written by the indexing model from the issue text.