Multiple scene URLs (#3852)

* Add URLs scene relationship
* Update unit tests
* Update scene edit and details pages
* Update scrapers to use urls
* Post-process scenes during query scrape
* Update UI for URLs
* Change urls label

pkg/models/update.go

@@ -110,3 +110,11 @@ type UpdateStrings struct {
 	Values []string               `json:"values"`
 	Mode   RelationshipUpdateMode `json:"mode"`
 }
+
+func (u *UpdateStrings) Strings() []string {
+	if u == nil {
+		return nil
+	}
+
+	return u.Values
+}