[ticket/12783] Move phpbb/phpbb require version to extra

PHPBB3-12783
[ticket/12783] Correctly use dataProviders and mark tests as incomplete

PHPBB3-12783
[ticket/12783] Move phpbb requirement to extra->soft-require

PHPBB3-12783
Merge pull request #2673 from nickvergessen/ticket/12783

Ticket/12783 Move require:phpbb/phpbb to extra:phpbb/phpbb in Extensions composer.json files

* nickvergessen/ticket/12783:
  [ticket/12783] Move phpbb requirement to extra->soft-require
  [ticket/12783] Correctly use dataProviders and mark tests as incomplete
  [ticket/12783] Move phpbb/phpbb require version to extra