[feature/auth-refactor] Refactor acp_board for new auth interface

Partially refactors acp_board for the new authentication interface.
Leaves some questionable if statements in the file.
Modifies the interface to correctly impletment the acp() method.
Modifies each provider to comply with the above mentioned interface
modification.

PHPBB3-9734

phpBB/includes/auth/provider_interface.php

@@ -58,5 +58,5 @@ interface phpbb_auth_provider_interface
 	 * This function is used to output any required fields in the authentication
 	 * admin panel. It also defines any required configuration table fields.
 	 */
-	public function acp();
+	public function acp($new);
 }