Add dozens of new integration tests to the GDScript test suite

This also ignores `.out` files in the file format static checks.

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

@@ -0,0 +1,14 @@
+enum Size {
+	S = -10,
+	M,
+	L = 0,
+	XL = 10,
+	XXL,
+}
+
+func test():
+	print(Size.S)
+	print(Size.M)
+	print(Size.L)
+	print(Size.XL)
+	print(Size.XXL)