chore: add GUT test framework

addons/gut/test/resources/per_test_assert_tracking.gd

@@ -0,0 +1,19 @@
+extends 'res://addons/gut/test.gd'
+
+func test_no_asserts():
+	pass
+
+func test_passing_assert():
+	assert_true(true, 'should pass')
+
+func test_failing_assert():
+	assert_true(false, 'should fail')
+
+func test_use_pass_test():
+	pass_test('this test passes')
+
+func  test_use_fail_test():
+	fail_test('this test fails')
+
+func test_use_pending():
+	pending('this is pending')