GPUBatch: Change preset managment system.

Now use a list of preset batches with a function to add new ones to this
list.

This removes the need of new functions all over the place to reset/exit.

source/blender/editors/include/UI_interface.h

@@ -1168,8 +1168,4 @@ void UI_tooltip_free(struct bContext *C, struct bScreen *sc, struct ARegion *ar)
 
 int UI_calc_float_precision(int prec, double value);
 
-/* UI Batches managment */
-void UI_widget_batch_preset_reset(void);
-void UI_widget_batch_preset_exit(void);
-
 #endif  /* __UI_INTERFACE_H__ */