Multiple image URLs (#4000)

* Backend changes - ported from scene impl
* Front end changes
* Refactor URL mutation code

pkg/models/jsonschema/scene.go

@@ -42,8 +42,10 @@ type Scene struct {
 	Title  string `json:"title,omitempty"`
 	Code   string `json:"code,omitempty"`
 	Studio string `json:"studio,omitempty"`
+
 	// deprecated - for import only
-	URL          string           `json:"url,omitempty"`
+	URL string `json:"url,omitempty"`
+
 	URLs         []string         `json:"urls,omitempty"`
 	Date         string           `json:"date,omitempty"`
 	Rating       int              `json:"rating,omitempty"`