v4: `tough-cookie`'s `CookieJar`s throw on invalid `Set-Cookie` response contents

[barjin]

As seen in apify/actor-scraper#236, the internal CookieJar can throw on a deformed Set-Cookie response from the server.

This error is now not caught anywhere and will kill the entire script if used, e.g., from a helper function (like discoverValidSitemaps).

We should treat all CookieJar methods as potentially throwing and only print warnings on thrown errors.