camel-netty: add support for native transport over KQueue

For now only Epoll is used as native transport for Netty. However that will not work on, for example, Mac OS, cause there we must use KQueue.

Also there are small problem with unixDomainSocketPath - several options is not appliable for *DomainSocketChannel. As can be seen from test NettyTCPSyncUDSTest, that produces 3 warnings for each request. I think it is ok just to not set them for consumer and producer.