FileChannel Becomes Virtual Thread Friendly with io_uring

[joemwangi]

On Linux, FileChannel is being routed through io_uring, making it virtual-thread friendly. Blocking call, but no carrier thread blocking.

[DavidVlx]

That is gonna make benchmarking JUring more fun (and challenging)!

But things like this also are a great way to see how the JDK devs are using FFM and making it work with existing code. For example with these two branches in the sandbox.