Fix timestamps and add IOCTL support for nbytes

[mmori7]

This commit adds functionality to the uvwasi poll_oneoff implementation by reporting the number of bytes available to read for file descriptors. It uses ioctl with FIONREAD on Unix-like systems and ioctlsocket for socket types on Windows to properly populate the nbytes field in FD_READ events. Additionally, it adds the necessary system headers for these ioctl calls with appropriate platform-specific handling. The change helps applications know exactly how many bytes they can read without blocking, improving performance by allowing them to allocate buffers of the correct size.

[Ronitsabhaya75]

The cross-platform approach with appropriate handling for both Unix and Windows is well-implemented, particularly the special consideration for Windows which doesn't support FIONREAD for non-socket descriptors. The error handling also looks robust, gracefully falling back to zero bytes when ioctl operations fail.

[cjihrig]

@mmori7 the CI is failing.