Changes 'beach bar' bitdomain ghost-spawners to be virtual_domain subtypes (#92177)

## About The Pull Request
Simple enough. This domain used just plain ghost spawners from the
lavaland ruin previously.
Now, it has `temp_body = TRUE`, allowing ghosts to return to their
original body after leaving the domain
_Alongside this it has unique little descriptions to cement it as NPC
actors_

This also adds a new `antag` variable to virtual_domain spawners, which
decides if they get the hunt-bitrunners antag datum _(default True, in
this case False)_

<h5>I did notice a few bugs while testing this, namely that temp_body
doesn't always work? I'm not coder enough to hunt down why and fix it
though... the two cases I noticed will be made into a bug report.</h5>

## Why It's Good For The Game
It feels weird that there's this temp_body ghost spawner stuff for
bitdomains, but it's not used in **all** the bitdomains. They don't last
that long, making them permanently kill old bodies feels odd.
This also sets up an easy var for other bit ghostroles to use if they
aren't explicitly antags hunting bitrunners, and don't need an antag
datum.
<img width="853" height="449" alt="image"
src="https://github.com/user-attachments/assets/d5761ac1-25bd-4ee5-b281-14fe4392479e"
/>

## Changelog
🆑
qol: made the Beach Bar bitdomain ghostrole spawners keep your old body
revivable (as other bitdomain spawners do)
/🆑

_maps/virtual_domains/beach_bar.dmm

@@ -648,7 +648,7 @@
 /area/virtual_domain/fullbright)
 "CA" = (
 /obj/structure/window/reinforced/spawner/directional/east,
-/obj/effect/mob_spawn/ghost_role/human/beach/lifeguard,
+/obj/effect/mob_spawn/ghost_role/human/virtual_domain/beach/lifeguard,
 /turf/open/floor/wood,
 /area/virtual_domain/fullbright)
 "CO" = (
@@ -875,7 +875,7 @@
 /turf/open/floor/light/colour_cycle/dancefloor_a,
 /area/virtual_domain/fullbright)
 "OE" = (
-/obj/effect/mob_spawn/ghost_role/human/beach{
+/obj/effect/mob_spawn/ghost_role/human/virtual_domain/beach{
 	dir = 4
 	},
 /turf/open/floor/wood,
@@ -906,7 +906,7 @@
 /area/virtual_domain/fullbright)
 "Pg" = (
 /obj/structure/sign/poster/official/high_class_martini/directional/west,
-/obj/effect/mob_spawn/ghost_role/human/bartender{
+/obj/effect/mob_spawn/ghost_role/human/virtual_domain/beach/bartender{
 	dir = 4
 	},
 /turf/open/floor/wood,