Add an export statement for the public extensions in the LocaleKeys class

[rekire]

I need to import always two imports to use my translations. Why not just adding an export to the generated file?

export 'package:easy_localization/src/public_ext.dart';

The line can be added here:

easy_localization/bin/generate.dart

Lines 175 to 181 in 25b7853

	var file = '''
	// DO NOT EDIT. This is code generated via package:easy_localization/generate.dart
	// ignore_for_file: constant_identifier_names
	abstract class LocaleKeys {
	''';

What do you think about it?