first pass at overrides rewrite

overrides now live in default.cfg inside TAG.pak

skeleton/SYSTEM/rg35xx/paks/Emus/GBA.pak/default.cfg

@@ -0,0 +1,14 @@
+-gpsp_save_method = libretro
+
+bind Up = UP
+bind Down = DOWN
+bind Left = LEFT
+bind Right = RIGHT
+bind Select = SELECT
+bind Start = START
+bind A Button = A
+bind B Button = B
+bind A Turbo = NONE:X
+bind B Turbo = NONE:Y
+bind L Button = L1
+bind R Button = R1