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/multiline_vector.gd

@@ -0,0 +1,17 @@
+func test():
+	Vector2(
+		1,
+		2
+	)
+
+	Vector3(
+		3,
+		3.5,
+		4,  # Trailing comma should work.
+	)
+
+	Vector2i(1, 2,)  # Trailing comma should work.
+
+	Vector3i(6,
+	9,
+		12)