Bug 1811633 - use updated, vendored version of PKI.js, remove old version r=Gijs
This also converts certDecoder.jsm to an ES module (as certDecoder.mjs) and
updates all uses of it.
Differential Revision: https://phabricator.services.mozilla.com/D167466
<!DOCTYPE html><html><head><title>resource test file</title></head><body></body></html>