[FEATURE] Support RDS Cluster with serverlessV2 mode

[smittnacht]

Is your feature request related to a problem?

It would be an awesome feature if we could also support RDS Clusters with serverless v2 engine-mode. This would be a great benefit for everyone who doesn't have steady load on its database and just has to ramp up when load peaks occure.

Describe the solution you'd like

When I'm correct all we need to do in order to support this instance type is introducing serverlessV2ScalingConfiguration parameter to the DBCluster ResourceDefinitions and Compositions

Additional context

Add any other context or screenshots about the feature request here.
https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2.create-cluster.html

[nabuskey]

I like the idea and we should support it given relative ease of implementation. Contribution is always welcome 😄