Argus: feat: give webhooks the option for accepting invalid HTTPS certs

webhooks currently fail to send if the cert is invalid (e.g. self-signed). This’ll add an allow_invalid_certs key to each webhook (with support for it in defaults/globally like notify)

Triggered by: _Originally posted by @samcro1967 in https://github.com/release-argus/Argus/issues/61#issuecomment-1139014316_

So for fun (I mean who doesn’t love certs), I changed webhook to use https. I get a different error in the webhook log when I execute the webhook from Argus, but I am guessing it is related to how I generated the self signed cert. Thought I would share in case it sheds any new light on the topic.

webhook log

[webhook] 2022/05/26 15:30:37 http: TLS handshake error from 172.18.0.14:41156: tls: oversized record received with length 21536

cert generation command

openssl req -new -x509 -sha256 -newkey rsa:2048 -nodes -keyout key.pem -days 9999 -out cert.pem`