Abort requests

[elbywan]

Use AbortController to add timeout and abort features.

Something like :

let w = wretch("...")
  .signal("...") // optional - ability to use a custom AbortSignal to abort multiple requests
  .get() 
     // before the fetch() call, the signal should be injected by wretch
     // if no signal was added, wretch creates an AbortController for the request
  .setTimeout(number /* aborts after N milliseconds */)
  .onAbort(AbortError => /* new catcher for aborted requests */)

let [ c, w ] = w.controller() /* ugly :( but seems like there is no better way of doing things */
 
w.res(r => /* should never be called ... */)
c.abort()