std: add Thread.Condition.timedWait (#11352)

* std: add Thread.Condition.timedWait

I needed the equivalent of `std::condition_variable::wait_for`, but it's missing in std.
This PR adds an implementation, following the status quo of using std.os.CLOCK.REALTIME in the pthread case (i.e. Futex)

A follow-up patch moving futex/condition stuff to monotonic clocks where available seems like a good idea.
This would involve conditionally exposing more functions and constants through std.c and std.os.
For instance, Chromium picks `pthread_cond_timedwait_relative_np` on macOS and `clock_gettime(CLOCK_MONOTONIC...)` on BSD's.

Tested on Windows 11, macOS 12.2.1 and Linux (with/without libc)

* Sleep in the single threaded case, handle timeout overflow in the Windows case and address a race condition in the AtomicCondition case.

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