Log warnings on startup when Kestrel is badly configured

This is a valid Kestrel configuration:

```cs
.ConfigureKestrel(options =>
{
options.Limits.Http2.MaxStreamsPerConnection = 32 * 1024;
});
```

Unfortunatly it will cause a client to send all its requests over one connection, causing contention and bad performance.

Consider:
* Analyizing Kestrel settings for ones that can be "valid" but misconfigured.
* Log warnings on startup when Kestrel has been configured with one of these values.