No converter for Uni types

When returning a Uni an error is thrown: org.apache.camel.NoTypeConversionAvailableException:
No type converter available to convert from type: io.smallrye.mutiny.operators.uni.UniOnItemTransformToUni to the required type: java.io.InputStream

Rest service EPs that fail

```
@Override
public void configure() throws Exception {
rest("/api")
.get("/movie/{index}")
.to("direct:multicast");
}
```
OR

```
@Override
public void configure() throws Exception {
from("platform-http:/platform/movie/{index}")
.to("direct:multicast");
}
```
The multicast route calls 3 routes that each call Resteasy Reactive clients that each return exchange with a Uni in the body. I use a GroupedExchangeAggregationStrategy to gather all the responses and then combine the Unis.

```
Agregation Processor
private void processAllExchanges(Exchange exchange,
MyResponse myResponse) {
List aListOfExchanges = getExchanges(exchange);

Uni movie = getUniFromExchange(aListOfExchanges, 0);
Uni episodes = getUniFromExchange(aListOfExchanges, 1);
Uni people = getUniFromExchange(aListOfExchanges, 2);

Uni combinedUni = Uni.combine()
.all()
.unis(movie, people, episodes)
.asTuple()
.onItem()
.transformToUni(tuple -> buildMyResponse(tuple, myResponse));

exchange.getMessage().setBody(combinedUni);
}
```
Is Camel Quarkus going to support returning reactive types as Resteasy Reactive does?

Start with the REST and platform-http route examples, then trace the multicast route and aggregation processor where the combined Uni is assigned to the exchange body. Reproduce the NoTypeConversionAvailableException and inspect how the response body is converted. Done means the supported behavior for reactive return types is established and covered by an appropriate test or documented limitation.

Written by the indexing model from the issue text.