Add the direction to the `MetricInfo` class.

[cwognum]

Context

An important piece of meta-data for a metric is whether it should be maximized or minimized. This e.g. allows for the automatic sorting of results.

Acceptance Criteria

• The direction attribute is added to the MetricInfo class.

Links

• Related PR on the hub-side: https://github.com/polaris-hub/polaris-hub/issues/161