Improve PHPStan level to 5

[mvorisek]

BC break - Model without table:

update code like: $m = new Model($db, false);
to: $m = new Model($db, ['table' => false]);

BC break - hasOne (Reference::$model can not be a string seed):

update code like: $this->hasOne('parent_folder_id', Folder::class];
to $this->hasOne('parent_folder_id', ['model' => [Folder::class]]);