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/spec/construct_internet_radio.go

@@ -0,0 +1,12 @@
+package spec
+
+import "go.senan.xyz/gonic/db"
+
+func NewInternetRadioStation(irs *db.InternetRadioStation) *InternetRadioStation {
+	return &InternetRadioStation{
+		ID:          irs.SID(),
+		Name:        irs.Name,
+		StreamURL:   irs.StreamURL,
+		HomepageURL: irs.HomepageURL,
+	}
+}