Request: make version data serialization customizable

[hagabaka]

Currently the serialization is done in VersionableTrait::versionablePostSave() with

$version->model_data = serialize($this->getAttributes());

and deserialization is done in Version::getModel() with

$model->fill(unserialize($modelData));

It would be nice if the method of serialization can be customized by overriding methods, for example to use JSONB column, or even a versions table with all the columns of the versioned model.

trait VersionableTrait
{
    protected function copyAttributesToVersion(Version $version)
    {
       $version->model_data       = serialize($this->getAttributes()); // default implementation
       // or
       $version->model_data = $this->getAttributesData(); // with a JSONB model_data column
       // or
       $version->fill($this->getAttributes()); // versions table with columns for all versioned attributes
    }
}

class Version
{
    protected function copyAttributesToVersionable($model)
    {
         $model->fill(unserialize($modelData));  // default implementation
         $model->fill($modelData); // with a JSONB model_data column
         $model->fill(array_only($this->getAttributes(), $versionedAttributes)); // versions table with columns for all versioned attributes
    }
}