Overhauls Custom Synthetic Code (#6803)

Loads custom synths from json or SQL as opposed to a txt file. Adds support for multiple borg sprites, ai chassis and custom ai hologram sprites as opposed to one sprite per player. Adds the ability to use custom pai sprites

code/controllers/configuration.dm

@@ -286,6 +286,7 @@ var/list/gamemode_cache = list()
 	var/rounds_until_hard_restart = -1 // Changes how often a hard restart will be executed.
 
 	var/docs_load_docs_from
+	var/load_customsynths_from
 	var/docs_image_host
 
 	var/ert_base_chance = 10
@@ -899,6 +900,8 @@ var/list/gamemode_cache = list()
 
 				if ("docs_load_docs_from")
 					docs_load_docs_from = value
+				if ("load_customsynths_from")
+					load_customsynths_from = value
 				if ("docs_image_host")
 					docs_image_host = value