feat(subsonic): add internet radio support

* Initial commit of internet radio support.

* Added first test for internet radio.

* Refactor to prepare for more test cases.

* Added a few more tests. Realized that I was not calling as admin so added ability to mock admin.

* Added more internet radio tests. Added proper JSON unmarshaling for ID.

* More test cases. Fixed some accidental tabs in files.

* Fixed some more tabs.

* lint fixes

* Changed placeholder for homepage URL to fit into box.

* Finished out internet radio test cases. Found a few bad error codes in internet radio AND podcasts (mea culpa).

* Realized that delete via website was not checking properly if id existed. Fixed.

gofmt

server/ctrlsubsonic/ctrl_test.go

@@ -69,6 +69,15 @@ func makeHTTPMock(query url.Values) (*httptest.ResponseRecorder, *http.Request)
 	return rr, req
 }
 
+func makeHTTPMockWithAdmin(query url.Values) (*httptest.ResponseRecorder, *http.Request) {
+	rr, req := makeHTTPMock(query)
+	ctx := req.Context()
+	ctx = context.WithValue(ctx, CtxUser, &db.User{IsAdmin: true})
+	req = req.WithContext(ctx)
+
+	return rr, req
+}
+
 func serveRaw(t *testing.T, contr *Controller, h handlerSubsonicRaw, rr *httptest.ResponseRecorder, req *http.Request) {
 	type middleware func(http.Handler) http.Handler
 	middlewares := []middleware{