GDScript: Improve call analysis

* Add missing `UNSAFE_CALL_ARGUMENT` warning.
* Fix `Object` constructor.
* Display an error for non-existent static methods.

modules/gdscript/tests/scripts/parser/features/dollar_node_paths.gd

@@ -5,9 +5,11 @@ func test():
 	# Create the required node structure.
 	var hello = Node.new()
 	hello.name = "Hello"
+	@warning_ignore("unsafe_call_argument")
 	add_child(hello)
 	var world = Node.new()
 	world.name = "World"
+	@warning_ignore("unsafe_call_argument")
 	hello.add_child(world)
 
 	# All the ways of writing node paths below with the `$` operator are valid.