Groundwork for Galarian Bird event

This adds the first half of an event where you will find the Galarian Birds. It is not finished yet.

It currently bugs out when Galarian Zapdos tries to run away and I don't know why. Frame-by-frame, it seems to be when the player has to move. I've tried different things to make this less bad, but they don't work.

Here's how it's meant to go:
1) Articuno flies away (done)
2) Zapdos barges past the player like Silver does in GSC (bugs out)
3) Moltres moves in front of the player and engages (not done)

If anyone has a better way to do this, please let me know!

Minor changes;
- Connection for Brunswick-Citrine looks nicer
- Celeste has a few changes to make the event run easier.

engine/overworld/auto_movement.asm

@@ -290,3 +290,8 @@ RivalIDs:
 	db OPP_RIVAL2
 	db OPP_RIVAL3
 	db -1 ; end
+
+RLEList_PlayerGZapMovement::
+	db D_DOWN, 1
+	db D_LEFT, 1
+	db -1 ; end

engine/overworld/player_animations.asm

@@ -252,7 +252,7 @@ DoFlyAnimation:
 	jr nz, DoFlyAnimation
 	ret
 
-LoadBirdSpriteGraphics:
+LoadBirdSpriteGraphics:: ; Made this farcallable for the Galarian Articuno animation.
 	ld de, BirdSprite
 	ld hl, vNPCSprites
 	lb bc, BANK(BirdSprite), 12