Add support for passing `node-fetch` options

[wintercounter]

The Deepl API after 10-15 translations hangs me for a while, sometimes even 5 minutes... I'd like to use AbortController and implement a retry/timeout feature for myself. (Or it could be part of the client as well).

[gillescoolen]

Understandable. I've got a busy weekend, so I can try and implement it next week. If you've got the time, PR's are always welcome :)

[wintercounter]

Which solution ur interested in? Only passing options or implementing timeout/retry? Anyway, for myself I think I won't use it, because it'll still count my character limit even for the "failed" requests.

[gillescoolen]

I think passing the options would be the better solution, as implementing a timeout or retry system might not be an option for everyone using the library.