Generated code should use `class_name` as a prefix for `LocalizationsDelegate`

[absar]

Generated code always generates AppLocalizationDelegate as LocalizationsDelegate name, which creates problems if two packages in a mono repo use the plugin to generate localizations it will create two delegates with the same name, instead it should use class_name as a prefix for LocalizationsDelegate e.g. if we provide MyLocalization as class_name it should generate MyLocalization class and MyLocalizationDelegate instead of always generating harcoded AppLocalizationDelegate