Add support for Netty's io_uring transport

[yuzawa-san]

Netty has recently added support for an experimental new type of transport which used Linux's io_uring facility. This PR allows users to pass in a IOUringEventLoopGroup without getting the "Unknown event loop group" exception. Given this is incubating within Netty, I added a optional, provided dependency if folks want to use it, they will have to include the proper dependency on their own. I used the epoll transport factory as a starting point (hence the copyright message).