Don't return AbortController

[fregante]

I think that accepting a signal and returning a new controller is a bit confusing. I think it should match native events more closely: just accept a signal.

It's more verbose, but it pushes people to use and reuse signals instead:

- const controller = delegate(…);
+ const controller = new AbortController()
+ delegate(…, {signal: controller.signal})
  controller.abort()

- const controller1 = delegate(…);
- const controller2 = delegate(…);
- controller1.abort()
- controller2.abort()
+ const controller = new AbortController()
+ delegate(…, {signal: controller.signal})
+ delegate(…, {signal: controller.signal})
+ controller.abort()

[stof]

I totally agree about that. It is weird to return a controller. No signal-based native API does that.

So 👍 for this change