[MIRROR] Fixes attempting to offset floating planes [MDB IGNORE] (#17745)

* Fixes attempting to offset floating planes (#71490)

## About The Pull Request

This is a dumb idea, and leads to fucked rendering on occasion

## Why It's Good For The Game

Fixes another portion of #70258, a player will no longer have a hidden
antag hud if they move down a z level after getting an antag. We were
trying to offset the floating plane of their image, and it went to shit.
Also fixes a bug with observers not having antag huds for the combo hud
to see. We were only giving them one on mind.on_transfer, rather then on
mind assignment. I hate mindcode

* Fixes attempting to offset floating planes

Co-authored-by: LemonInTheDark <58055496+LemonInTheDark@users.noreply.github.com>

code/controllers/subsystem/mapping.dm

@@ -112,6 +112,8 @@ SUBSYSTEM_DEF(mapping)
 	true_to_offset_planes["[FLOAT_PLANE]"] = list(FLOAT_PLANE)
 	plane_to_offset["[FLOAT_PLANE]"] = 0
 	plane_offset_blacklist = list()
+	// You aren't allowed to offset a floatplane that'll just fuck it all up
+	plane_offset_blacklist["[FLOAT_PLANE]"] = TRUE
 	render_offset_blacklist = list()
 	critical_planes = list()
 	create_plane_offsets(0, 0)

code/datums/mind/initialization.dm

@@ -9,6 +9,8 @@
 	if(!mind.name)
 		mind.name = real_name
 	mind.set_current(src)
+	// There's nowhere else to set this up, mind code makes me depressed
+	mind.antag_hud = add_alt_appearance(/datum/atom_hud/alternate_appearance/basic/antagonist_hud, "combo_hud", mind)
 
 /mob/living/carbon/mind_initialize()
 	..()