Move `config/file_types.php` above Pkg `on_start`

Move `config/file_types.php above `startup/packages.php` to allow
`Package::on_start()` to override file types with
`FileTypeList::define()`
Merge pull request #1151 from mkly/move_config_file_types_above_on_start

Move `config/file_types.php` above Pkg `on_start`