feat: expose album, song and artist annotations in the RESTful API

model/annotation.go

@@ -7,3 +7,7 @@ type AnnotatedRepository interface {
 	SetStar(starred bool, itemIDs ...string) error
 	SetRating(rating int, itemID string) error
 }
+
+// While I can't find a better way to make these fields optional in the models, I keep this list here
+// to be used in other packages
+var AnnotationFields = []string{"playCount", "playDate", "rating", "starred", "starredAt"}