Puts Deathmatch map names, keys in line with each other (WARNING: LETHAL DOSES OF SNAKECASE INSIDE) (#81970)

## About The Pull Request

This does a bunch of cleaning up with regards to Deathmatch map names,
keys, filenames, etc.

Quick summary -- Filenames/map keys now have underscore spacing and have
been mostly. Deathmatch now has its own root folder instead of just
being in map_files (this might not really be necessary idk why I did
this). Map filenames and map keys should be consistent now in terms of
spacing, capitalization, and what they actually refer to.

## Why It's Good For The Game

"Backalley" is actually called "raidthebase" internally. Arenastation
doesn't use the "Arena" map, instead using the one called "Star Wars"
(The underground thunderdome uses the "Arena" map, actually). Guess
which one was internally called "chinatown" and get a prize!

This makes a lot of the map stuff related to Deathmatch easier to read
and less inconsistent. I know consistency isn't super important but it
annoys me personally and I need to address it.
## Changelog
🆑 Rhials
code: Deathmatch files, map names, and keys should all be consistent
now.
/🆑

code/modules/deathmatch/deathmatch_maps.dm

@@ -1,11 +1,13 @@
 /datum/lazy_template/deathmatch //deathmatch maps that have any possibility of the walls being destroyed should use indestructible walls, because baseturf moment
-	map_dir = "_maps/map_files/Deathmatch"
+	map_dir = "_maps/deathmatch"
 	place_on_top = TRUE
 	/// Map UI Name
 	var/name
 	/// Map Description
 	var/desc = ""
+	/// Minimum players for this map
 	var/min_players = 2
+	/// Maximum players for this map
 	var/max_players = 2 // TODO: make this automatic.
 	/// The map will end in this time
 	var/automatic_gameend_time = 8 MINUTES
@@ -26,24 +28,24 @@
 	desc = "Dark maintenance tunnels, floor pills, improvised weaponry and a bloody beatdown. Welcome to assistant utopia."
 	max_players = 8
 	allowed_loadouts = list(/datum/outfit/deathmatch_loadout/assistant)
-	map_name = "Maint_Mania"
-	key = "Maint_Mania"
+	map_name = "maint_mania"
+	key = "maint_mania"
 
 /datum/lazy_template/deathmatch/osha_violator
 	name = "OSHA Violator"
 	desc = "What would Engineering be without an overly complicated engine, with conveyor belts, emitters and shield generators sprinkled about? That's right, not Engineering."
 	max_players = 10
 	allowed_loadouts = list(/datum/outfit/deathmatch_loadout/assistant)
-	map_name = "OSHA_Violator"
-	key = "OSHA_Violator"
+	map_name = "OSHA_violator"
+	key = "OSHA_violator"
 
 /datum/lazy_template/deathmatch/the_brig
 	name = "The Brig"
 	desc = "A recreation of MetaStation Brig."
 	max_players = 12
 	allowed_loadouts = list(/datum/outfit/deathmatch_loadout/assistant)
-	map_name = "The_Brig"
-	key = "The_Brig"
+	map_name = "meta_brig"
+	key = "meta_brig"
 
 /datum/lazy_template/deathmatch/shooting_range
 	name = "Shooting Range"
@@ -61,8 +63,8 @@
 	desc = "Presenting the Security Ring, ever wanted to shoot people with disablers? Well now you can."
 	max_players = 4
 	allowed_loadouts = list(/datum/outfit/deathmatch_loadout/securing_sec)
-	map_name = "SecuRing"
-	key = "SecuRing"
+	map_name = "secu_ring"
+	key = "secu_ring"
 
 /datum/lazy_template/deathmatch/instagib
 	name = "Instagib"
@@ -80,29 +82,29 @@
 	map_name = "mech_madness"
 	key = "mech_madness"
 
-/datum/lazy_template/deathmatch/sniperelite
+/datum/lazy_template/deathmatch/sniper_elite
 	name = "Sniper Elite"
 	desc = "Sound of gunfire and screaming people make my day"
 	max_players = 8
 	allowed_loadouts = list(/datum/outfit/deathmatch_loadout/operative/sniper)
-	map_name = "Sniper_elite"
-	key = "Sniper_elite"
+	map_name = "sniper_elite"
+	key = "sniper_elite"
 
 /datum/lazy_template/deathmatch/meatower
 	name = "Meat Tower"
 	desc = "There can only be one chef in this kitchen"
 	max_players = 8
 	allowed_loadouts = list(/datum/outfit/deathmatch_loadout/chef)
-	map_name = "meatower"
-	key = "meatower"
+	map_name = "meat_tower"
+	key = "meat_tower"
 
 /datum/lazy_template/deathmatch/sunrise
 	name = "Sunrise"
 	desc = "DEHUMANIZE YOURSELF AND FACE TO BLOODSHED DEHUMANIZE YOURSELF AND FACE TO BLOODSHED DEHUMANIZE YOURSELF AND FACE TO BLOODSHED DEHUMANIZE YOURSELF AND FACE TO BLOODSHED"
 	max_players = 8
 	allowed_loadouts = list(/datum/outfit/deathmatch_loadout/samurai)
-	map_name = "chinatown"
-	key = "chinatown"
+	map_name = "sunrise"
+	key = "sunrise"
 
 /datum/lazy_template/deathmatch/starwars
 	name = "Arena Station"
@@ -124,10 +126,10 @@
 		/datum/outfit/deathmatch_loadout/battler/tgcoder,
 		/datum/outfit/deathmatch_loadout/naked,
 	)
-	map_name = "starwars"
-	key = "starwars"
+	map_name = "arena_station"
+	key = "arena_station"
 
-/datum/lazy_template/deathmatch/arenaplatform
+/datum/lazy_template/deathmatch/underground_thunderdome
 	name = "Underground Thunderdome"
 	desc = "An illegal underground thunderdome, for larger amounts of murder."
 	max_players = 15
@@ -135,10 +137,10 @@
 		/datum/outfit/deathmatch_loadout/operative,
 		/datum/outfit/deathmatch_loadout/naked,
 	)
-	map_name = "arena"
-	key = "arena"
+	map_name = "underground_arena"
+	key = "underground_arena"
 
-/datum/lazy_template/deathmatch/raidthebase
+/datum/lazy_template/deathmatch/backalley
 	name = "Backalley"
 	desc = "You are not built for these streets."
 	max_players = 8
@@ -146,5 +148,5 @@
 		/datum/outfit/deathmatch_loadout/assistant,
 		/datum/outfit/deathmatch_loadout/naked,
 	)
-	map_name = "raidthebase"
-	key = "raidthebase"
+	map_name = "backalley"
+	key = "backalley"