(aws-elasticloadbalancingv2): A way to get the rules of a load balancer listener

It would be great if there was a way to get all the rules given a load balancer listener.

### Use Case

Since CDK doesn't calculate the priority of the next rule itself (another feature request [here](https://github.com/aws/aws-cdk/issues/12067)), I need to do that myself, and to do that I first need to find out what the highest priority rule currently is.

Right now I don't see any other way of achieving this besides using the SDK. The IApplicationListener doesn't provide them.

### Proposed Solution

IApplicationListener should return all the rules with the whole detail tree (rule, condition, action, TG etc)

### Other

* [ ] :wave: I may be able to implement this feature request
* [ ] :warning: This feature might incur a breaking change

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This is a :rocket: Feature Request

Start at the IApplicationListener interface and inspect the existing AWS SDK-based listener and rule access patterns. Compare the listener's current API with the SDK operation that lists rules, including conditions, actions, and target groups. Done means callers can retrieve all rules for a listener with the requested detail tree and can determine the highest existing priority.

Written by the indexing model from the issue text.