#2559. Add augmenting itself tests (#2567)

LanguageFeatures/Augmentation-libraries/defining_augmentation_A05_t01.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion It is a compile-time error if a library tries to augment itself
+///
+/// @description Checks that it is a compile-time error if a library tries to
+/// augment itself
+/// @author sgrekhov22@gmail.com
+/// @issue 55168, 55169
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'defining_augmentation_A05_t01.dart';
+//               ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+import augment 'defining_augmentation_A05_t01.dart';
+//              ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+main() {
+}

LanguageFeatures/Augmentation-libraries/defining_augmentation_A05_t02.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion It is a compile-time error if a library tries to augment itself
+///
+/// @description Checks that it is a compile-time error if a library tries to
+/// augment itself. Test cycling dependency
+/// @author sgrekhov22@gmail.com
+/// @issue 55168, 55169
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'defining_augmentation_A05_t02_lib.dart';
+//               ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+import augment 'defining_augmentation_A05_t02_lib.dart';
+//              ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+main() {
+}

LanguageFeatures/Augmentation-libraries/defining_augmentation_A05_t02_lib.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion It is a compile-time error if a library tries to augment itself
+///
+/// @description Checks that it is a compile-time error if a library tries to
+/// augment itself. Test cycling dependency
+/// @author sgrekhov22@gmail.com
+/// @issue 55168, 55169
+
+// SharedOptions=--enable-experiment=macros
+
+library augment 'defining_augmentation_A05_t02.dart';
+//               ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+import augment 'defining_augmentation_A05_t02.dart';
+//              ^
+// [analyzer] unspecified
+// [cfe] unspecified