Sandboxes: a timer wakes a sandbox that paused while idle

When a sandbox pauses because it is idle, Runtime records when the next timer of a process in it is due (a sleep, a wait with a timeout, a timerfd, alarm or a POSIX timer) and wakes the sandbox about one second before then. Only timers due within 29 minutes of the pause, and pending for the whole idle time, count, so a process that wakes every few seconds does not keep waking it. A sandbox with no pending timer stays paused. A pause you request, a pause at the end of a time limit or of credit, and a sandbox with autoWake: false are not woken by timers. See timers wake an idle sandbox.