[ticket/11335] (extension manager/finder) Make php_ext 'php,' not '.php'

PHPBB3-11335
[ticket/11335] (hook finder) Make php_ext 'php,' not '.php'

PHPBB3-11335
[ticket/11335] (kernel request subscriber) Make php_ext 'php,' not '.php'

PHPBB3-11335
[ticket/11335] (avatars) Make php_ext 'php,' not '.php'

PHPBB3-11335