Add WithMonitoringEndpoint to NatsServerResource

## Background and Motivation

Nats supports a monitoring endpoint when starting with command line argument "-m {port}". Not only can it be used by other dashboards or connected to tracings. It also provides a simplistic UI that provide stats in json format. Additional it also provides an explicit health check route (the current health check periodically propes an connection) which can be used to optionally (?) use it as aspire health check.

I have implementation ready and can send a PR.

## Proposed API
```diff
namespace Aspire.Hosting;

public static class NatsBuilderExtensions
{
+ public static IResourceBuilder WithMonitoringEndpoint(this IResourceBuilder builder, int? port = null, bool addHealthCheckUsingMonitoringEndpoint = true)
}
```

## Usage Examples
```csharp
var nats = builder.AddNats("nats")
.WithMonitoringEndpoint();
```

## Alternative Designs

Don't know of useful alternative forms

## Risks

Note from [monitoring documentation](https://docs.nats.io/running-a-nats-service/nats_admin/monitoring):

> nats-server does not have authentication/authorization for the monitoring endpoint. When you plan to open your nats-server to the internet make sure to not expose the monitoring port as well. By default, monitoring binds to every interface 0.0.0.0 so consider setting monitoring to localhost or have appropriate firewall rules.

Btw. can someone please reopen the PR https://github.com/dotnet/aspire/pull/6056, I don't have permission to do it.