webhook deliveries: show user's endpoint response

[codenoid]

fix for #3916

[vercel]

@codenoid is attempting to deploy a commit to the polar-sh Team on Vercel.

A member of the Team first needs to authorize it.

[birkjernstrom]

Wow @codenoid – really impressed how you've jumped into the codespace and provided several PRs already 💪🏼🙏🏼 I'll review them and hope to merge many of them soon.

Have you joined our Discord btw? Would be great to chat 1-1 :)
dub.sh/polar-discord

Regarding this one: I need to think on it a little bit to ensure we avoid some security concerns. I think we'd at least want to make sure we only accept JSON responses and at a certain size. Otherwise, it can easily become problematic. But need to think and look at what others are doing before I give my final say :)