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/ctrladmin/ctrl.go

@@ -123,6 +123,7 @@ type templateData struct {
 	SelectedUser           *db.User
 
 	Podcasts []*db.Podcast
+	InternetRadioStations []*db.InternetRadioStation
 }
 
 type Response struct {