Issue #3091336: Use a proper language fallback mechanism for path.alias_repository service

core/modules/language/src/ConfigurableLanguageManager.php

core/modules/path/src/Plugin/Field/FieldType/PathItem.php

...es/path/tests/src/Kernel/PathItemLanguageFallbackTest.php

core/modules/path/tests/src/Kernel/PathItemTest.php

core/modules/path_alias/path_alias.services.yml

core/modules/path_alias/src/AliasRepository.php

..._fallback_test/path_alias_language_fallback_test.info.yml

...ge_fallback_test/path_alias_language_fallback_test.module

...path_alias/tests/src/Kernel/AliasLanguageFallbackTest.php

...s/tests/src/Traits/PathAliasLanguageFallbackTestTrait.php