GDScript: Add support for variadic functions

modules/gdscript/tests/scripts/analyzer/errors/variadic_functions.gd

@@ -0,0 +1,22 @@
+class A:
+	func f1(x: int, ...args: Array) -> void:
+		prints(x, args)
+
+	func f2(x: int, ...args: Array) -> void:
+		prints(x, args)
+
+class B extends A:
+	func f1(x: int, y: int, ...args: Array) -> void:
+		prints(x, y, args)
+
+	func f2(x: int) -> void:
+		print(x)
+
+func g(...args: int):
+	pass
+
+func h(...args: Array[int]):
+	pass
+
+func test():
+	pass