Support file-less scenes. Add scene split, merge and reassign file (#3006)

* Reassign scene file functionality
* Implement scene create
* Add scene create UI
* Add sceneMerge backend support
* Add merge scene to UI
* Populate split create with scene details
* Add merge button to duplicate checker
* Handle file-less scenes in marker preview generate
* Make unique file name for file-less scene exports
* Add o-counter to scene update input
* Hide rescan for file-less scenes
* Generate heatmap if no speed set on file
* Fix count in scene/image queries

pkg/models/stash_ids.go

@@ -9,3 +9,14 @@ type UpdateStashIDs struct {
 	StashIDs []StashID              `json:"stash_ids"`
 	Mode     RelationshipUpdateMode `json:"mode"`
 }
+
+// AddUnique adds the stash id to the list, only if the endpoint/stashid pair does not already exist in the list.
+func (u *UpdateStashIDs) AddUnique(v StashID) {
+	for _, vv := range u.StashIDs {
+		if vv.StashID == v.StashID && vv.Endpoint == v.Endpoint {
+			return
+		}
+	}
+
+	u.StashIDs = append(u.StashIDs, v)
+}