Enable `platform-http-vertx` route processing to run on IO threads

Relates to a discussion on Zulip here:

https://camel.zulipchat.com/#narrow/stream/257302-camel-quarkus/topic/Fully.20Non-Blocking.20Reactive

Currently, all of the route processing that comes after `from("platform-http")` is done on a worker thread:

https://github.com/apache/camel/blob/main/components/camel-platform-http-vertx/src/main/java/org/apache/camel/component/platform/http/vertx/VertxPlatformHttpConsumer.java#L168-L221

I wonder if we should introduce an option that determines whether a worker or IO thread is used. E.g if folks know the downstream route processing will not block, then they can choose to have the work done on an IO thread.