Show gas icons in resource displays

tests/_lab_menu_preview.gd

@@ -12,6 +12,7 @@ func _ready() -> void:
 	GameState.transporters.clear()
 	GameState.reset_progression()
 	GameState.rocks = 240
+	GameState.gas = 36
 	GameState.unlocked = ["shipyards", "vessel_science"]
 	var main: Node = load("res://Main.tscn").instantiate()
 	add_child(main)
@@ -19,6 +20,7 @@ func _ready() -> void:
 	var lab_id: int = int(GameState.buildings[-1].id)
 	GameState.deposit_to_building(lab_id, 18)
 	GameState.fleet_cargo = 12
+	GameState.fleet_gas_cargo = 8
 	# A level already bought, so the list shows both a researched and an
 	# unresearched line rather than a uniform page of zeroes.
 	GameState.vessel_levels["int_damage"] = 1

tests/_transfer_menu_preview.gd

@@ -13,13 +13,16 @@ func _ready() -> void:
 	GameState.extractors.clear()
 	GameState.transporters.clear()
 	GameState.rocks = 180
+	GameState.gas = 36
 	GameState.fleet_cargo = 24
+	GameState.fleet_gas_cargo = 12
 	GameState.unlocked = ["shipyards", "logistics", "freight"]
 	var main: Node = load("res://Main.tscn").instantiate()
 	add_child(main)
 	main.get_node("BuildingField").place(GameState.BUILDING_SHIP_CRAFTER, Vector2(400.0, 0.0))
 	var crafter_id: int = int(GameState.buildings[-1].id)
 	GameState.deposit_to_building(crafter_id, 42)
+	GameState.find_building(crafter_id).gas_stock = 18
 	var bc: Node = main.get_node("BuildController")
 	bc.transfer_building_id = crafter_id
 	main.get_node("UI/TransferMenu").visible = true