Google Code-in

See https://phabricator.wikimedia.org/T120644

The GoogleLogin extension needs to be converted to use the new extension registration system: https://www.mediawiki.org/wiki/Extension:GoogleLogin

Basic documentation about the extension registration system is at https://www.mediawiki.org/wiki/Extension_registration

The convertExtensionToRegistration.php script can be used to create an extension.json file, though it may not work perfectly and could trigger errors. Use the validateRegistrationFile.php script to make sure your script follows the correct schema.

The PHP entry point will need to be kept and there will be duplication of information until Wikimedia config is updated.

Please add Florianschmidtwelzow as a reviewer in Wikimedia Gerrit to conversion patches and feel free to ask him if something is unclear, some documentation is missing, etc.