Add animation reset track feature

As a bonus, to have consistency between use Beziers and create insert tracks, use Beziers also gets a default via editor settings that is used when the confirmation dialog is disabled, instead of just falling back to creating non-Bezier tracks.

editor/plugins/animation_player_editor_plugin.h

@@ -105,6 +105,8 @@ class AnimationPlayerEditor : public VBoxContainer {
 	Label *name_title;
 	UndoRedo *undo_redo;
 	Ref<Texture2D> autoplay_icon;
+	Ref<Texture2D> reset_icon;
+	Ref<ImageTexture> autoplay_reset_icon;
 	bool last_active;
 	float timeline_position;