Bill's Garden, add Rowan NPC

Rowan NPC added to Cinnabar Lab, just a little cute thing.

Bill's Garden could see many revisions, what's here is the bare minimum. Here's what's done:
- Nidorino NPC blocks it off and is unlocked in the post-game. This currently contradicts the myth - I have a plan for this soon.
- Wild Pokemon are the "non-reproducibles" given in Stadium; starters and eevee are mandatory given those were common in the myth
- Hisui forms should be added when possible
- I had to remake Martha's map in the forest tileset so leaving would be possible
- Everything is at a point where it functions

constants/hide_show_constants.asm

@@ -247,4 +247,5 @@ DEF SHOW EQU $15
 	const HS_ROUTE_1_OAK				; EB
 	const HS_MT_MOON_CRATER_GUARD		; EC
 	const HS_MANSION_GUARD				; ED
+	const HS_BILLS_NIDORINO				; EE
 DEF NUM_HS_OBJECTS EQU const_value

constants/map_constants.asm

@@ -263,7 +263,7 @@ DEF FIRST_INDOOR_MAP EQU const_value
 	mapconst CELADON_UNIVERSITY_OUTSIDE,    20, 21 ; $F1	- Was UNUSED_MAP_F1
 	mapconst CELADON_UNIVERSITY_INSIDE,     10, 11 ; $F2	- Was UNUSED_MAP_F2
 	mapconst CELADON_UNIVERSITY_POKECENTER,  4,  7 ; $F3	- Was UNUSED_MAP_F3
-	mapconst UNUSED_MAP_F4,                  0,  0 ; $F4	- Unused, will be Bill's Garden
+	mapconst BILLS_GARDEN,                   9,  8 ; $F4	- Was UNUSED_MAP_F4
 	mapconst LORELEIS_ROOM,                  6,  5 ; $F5
 	mapconst BRUNOS_ROOM,                    6,  5 ; $F6
 	mapconst AGATHAS_ROOM,                   6,  5 ; $F7	- Maps F8 - FE currently have no data