[ticket/11755] MySQL upgrader out of date

De-duplicating code from create_schema_files, mysql_upgrader.

New file phpbb/db/schema_data which contains all the current schema data.

New function in db_tools public static function get_dbms_type_map() to make the
type map available everywhere (without requiring $db be setup already)

http://tracker.phpbb.com/browse/PHPBB3-11755