Restore the ability to use reals for timeout in the Socket module

[e-kayrakli]

It looks like the Socket module (or something else) had the capability to cast a real into a struct timeval at some point. Then that got removed. I haven't followed the breadcrumbs to learn the full story. However, the Socket module had some interface where real is accepted for a timeout, which then casted to struct timeval using that now-nonexistent cast.

The current behavior on main is that the interfaces that accepts reals for timeouts simply don't resolve and they are untested. This PR adds the capability back via a private helper instead of a cast, and expands some of the timeout testing.

Test:

• local test/library/package/Socket