Non-HTTP API support.

The open API is designed for HTTP-based requests. Knot.x should be adapted to support two-way communication via websites.

**Describe the solution you'd like**
The proposition is to add a `customRoutes` configuration similar to the Open API one.

```
httpRoutingOperations = { }
customRoutes = [ ROUTE, ROUTE ]
```

where ROUTE would be:

```
{
"path": "/eventbus/",
"handlers": [ ... ]
}
```

**Describe alternatives you've considered**
Run another Vert.x server on a different port.

**Additional context**
Add any other context or screenshots about the feature request here.

No files or tests are named. Begin by locating the existing Open API routing configuration and the Vert.x server entry point; done would require a defined customRoutes design and tests demonstrating the proposed handlers support two-way communication.

Written by the indexing model from the issue text.