[decomp] add import statements for art groups (#1372)

* new code

* update goal_src and remove all_imports

* update reference

* add decompiler list of imports

* deduplicate and move below decomp begins

test/decompiler/reference/engine/ui/hud-classes_REF.gc

@@ -1,6 +1,8 @@
 ;;-*-Lisp-*-
 (in-package goal)
 
+(import "goal_src/import/fuelcell-naked-ag.gc")
+
 ;; failed to figure out what this is:
 (defpartgroup group-part-hud-pickup
   :id 75