Cancellation support for createResource

[hackwaly]

Use case: Auto cancel ajax request on dispose.

[atk]

There is @solid-primitives/fetch that allows you to make a request abortable via its composable withAbort modifier. If used inside a reactive context, it will already auto-abort.

[ryansolid]

This has always confused me a little. Isn't it too late to cancel at that point? Like the request has gone out. You don't want it to affect your app, but like that ship has sailed.

[hackwaly]

This can save a lot server resources any way.