fix(core): allow controll by signal from fetchOptions

[rexpan]

Resolves #3377

Summary

The signal passed from fetchOptions by user be ignored and overrided.

Set of changes

Listen to abort event from user passed signal and abort the current request.

[tatianajiselle]

I can confirm that I am experiencing the bug myself, would appreciate this being resolved.

[kitten]

@tatianajiselle I left a comment on #3377 trying to answer all three streams of this discussion, but basically, I don't consider this a bug or missing feature right now, and instead, would recommend to write a fetch wrapper and pass that to the Client. There's a further explanation in the issue's comment, but I wouldn't consider using the AbortSignal that's passed in as more useful or more correct, given that it isn't more practical than either a custom exchange or a fetch wrapper, and also isn't a practical public API

Edit: Also, to clarify, I wasn't sure whether the original issue in #3377 and the Discord thread were from the same team, so I assumed as much given the timing 😅 But apologies if they're not

[tatianajiselle]

all good! moving convo to #3377 for simplicity

[kitten]

As per the conversation in #3377, since signal is not part of the public API (1) because HTTP is not assumed and hence fetchOptions is limited, and (2) since it's not expected to set up a timeout or otherwise pass an AbortSignal in the UI layer to the Client, what this change adds is not expected to work.