[tcgc] change response structure to mapping with key number, status code range, or *

[iscai-msft]

The HttpOperationResponse that @typespec/http returns to us has property .statusCodes on each of them. The type of this is HttpStatusCodeRange | number | "*". On the tcgc side, we're creating a map to more easily map status codes to the expected responses. We used to map this as a Record of number | string (we would do some processing magic for status codes). However, we've decided to switch to a Map since it can handle complex key inputs, and made the key inputs the same as the .statusCodes type from tsp for fidelity.

All instances of passing the responses to Object.keys(responses) / Object.values(responses) / Object.items(responses) should be changed, and you can directly access the native .keys(responses) etc

[azure-sdk]

All changed packages have been documented.

[azure-sdk]

You can try these changes at https://cadlplayground.z22.web.core.windows.net/typespec-azure/prs/515/

Check the website changes at https://tspwebsitepr.z22.web.core.windows.net/typespec-azure/prs/515/