Issue #3029461 by gilmord, Ressinel, artem_sylchuk, manuel.adan: Move message...
requested to merge issue/private_message-3317985:private_message_fix_phpcs-33179853317985 into 3.0.x
Issue #3029461 by gilmord, Ressinel, artem_sylchuk, manuel.adan: Move the message notification system to a submodule
Added phpcs fix, according to maintainer comment - only fixes for branch 8.x-2.x-dev, so added changes for branch 3.0.x.