[tcgc] Pending Design Issues

[iscai-msft]

• remove arm from SdkClientType [tcgc] deprecate .arm on SdkClientType #504
• endpoint on SdkClientType. Should it be string | undefined? Can we have a client with no endpoint. If @server is there with a full-value, then endpoint is a required initialization property. If it is there with a default value, then it's an optional initialization property (NEW DESIGN) [tcgc] create endpoint type #474
• Finalize on design structure for responses and exceptions (map of range to response)
• Should isError be something in usage? No. see if you can remove it completely from the returned tcgc type [tcgc] deprecate .isError on SdkModelType #503
• Should isFormDataType also be something in usage? Yes, call it MultipartFormData [tcgc] add UsageFlags.MultipartFormData and deprecate .isFormDataType #502
• Patch in UsageFlags [tcgc] add UsageFlags.JsonMergePatch #455. Call it JsonMergePatch
• Should we make a separate discriminatedModel type with all of the polymorphic specific properties in it? No, let's keep it simple
• Should a client have it's parent client on it? Or should .clients only show top-level clients. ANSWER: no parent client, but all clients should have initialization. If it's an operation group, access will be internal. Don't generate recursively (recommendation) [tcgc] make initialization required on all clients, add access to disambiguate #513
• clientaccessor or clientgetter / another name (keep it clientaccessor
• What should we do for NoAuth. See what handwritten sdks do in storage, bc there is a use case for this. Just don't return credential as part of initialization
• Nullability. Should it go on props / params or on the original type. Main use case for putting it on the type is for array types, to distinguish whether the array is nullable, or if its items are nullable [tcgc] move nullable onto params and responses #447
• Rename .nameInClient to .name https://github.com/Azure/typespec-azure/pull/445/files
• Make .generatedName a bool and .name a required prop [tcgc] Fix generated name #444
• Remove getParameterMapping and getResponseMapping, put directly on the types
• Rename initialOperation -> operation for SdkLroServiceMethod
• Single bodyParam
• sourceModel on a property SdkBodyModelPropertyType`