OCSP: Indicate if Must-Staple was claimed, but no staple was provided

[James-E-A]

https://discourse.mozilla.org/t/webrequest-getsecurityinfo-certificates-pem-format-or-at-least-include-extensions/67138/2

Blocks #7

[James-E-A]

…turns out, I'm just blind.

await webRequest.getSecurityInfo(… rawDER: true});

[James-E-A]

it's dangerous to go alone; take this!

https://github.com/lapo-luchini/asn1js/blob/1.2.1/asn1.js

[James-E-A]

…if we're doing the ASN parsing ourselves, how much will we have to worry about potentially malformed or malicious data?

Does Firefox at least enforce its being DER?