New sand and water sprites (ported from Bay) (#75254)

## About The Pull Request
Ports over new water sprites originally made by Flashkirby in
https://github.com/Baystation12/Baystation12/pull/3724

Also made some code adjustments because they don't have that weird
in-between sprite that the old water had.

## Why It's Good For The Game

![image](https://user-images.githubusercontent.com/66640614/236734326-fd492313-270e-4ba5-ae68-3e5adf8d3c89.png)
This could be us but you're still using those jank-ass old water sprites
:\

## Changelog
🆑 Tattle, Flashkirby
sound: increased the volume of the water step noises
image: ported over bay's water sprites
/🆑

---------

Co-authored-by: tattle <article.disaster@gmail.com>

code/modules/holodeck/turfs.dm

@@ -70,24 +70,24 @@
 	gender = PLURAL
 	name = "sand"
 	desc = "This is better than a vacation, since you're still getting paid."
-	icon = 'icons/misc/beach.dmi'
+	icon = 'icons/turf/sand.dmi'
 	icon_state = "sand"
 	bullet_bounce_sound = null
 	tiled_dirt = FALSE
 
-/turf/open/floor/holofloor/beach/coast_t
+/turf/open/floor/holofloor/beach/coast
 	gender = NEUTER
 	name = "coastline"
-	icon_state = "sandwater_t"
+	icon = 'icons/turf/beach.dmi'
+	icon_state = "beach"
 
-/turf/open/floor/holofloor/beach/coast_b
-	gender = NEUTER
-	name = "coastline"
-	icon_state = "sandwater_b"
+/turf/open/floor/holofloor/beach/coast/corner
+	icon_state = "beach-corner"
 
 /turf/open/floor/holofloor/beach/water
 	name = "water"
 	desc = "Gives the impression you can walk on water. Chaplains love it."
+	icon = 'icons/turf/beach.dmi'
 	icon_state = "water"
 	bullet_sizzle = TRUE