feat req: provide signal opt

[antongolub]

          Why support `ac` instead of `signal`, for which JavaScript has methods to work with?

const p1 = $({ signal: AbortSignal.timeout(100) })`sleep 9999`
 
// and

const ac = new AbortController()
const p2 = $({ 
  signal: AbortSignal.any(AbortSignal.timeout(1000), ac.signal)
})`sleep 9999`

button.addEventListener('click', () => {
  ac.abort()
})

Originally posted by @ftoh in #734 (comment)