Drags death sounds out of RenderInfantry into a separate DeathSounds trait.

Play death sounds with a new PlayVoiceLocal so they don't use full volume regardless of position relative to camera.
Adds option for alternative burn and zap death sounds.
Renames RenderInfantry's UseInfantryDeath trait to SpawnsCorpse.

Removes hack from ra desert shellmap.

mods/ra/maps/desert-shellmap/map.yaml

@@ -1308,7 +1308,8 @@ Rules:
 			SpeedModifier:
 	^Infantry:
 		ScriptInvulnerable:
-		-Selectable: # short-term hack to make infantry not play die sounds until we fix RenderInfantry
+		DeathSounds:
+			DeathVoice:
 		GivesBounty:
 			Percentage: 0
 		GainsExperience: