We currently annotating xpcshell tests because new HttpServer() does not support https. Given that the web is migrating to http I think it's worth the investment so that our HTTPServer supports https as well - thank you!

The "HTTPServer` used in xpcshell tests (notably extension tests) is https://searchfox.org/mozilla-central/source/netwerk/test/httpserver/httpd.js

The replacement/improvement should ideally have a compatible API.

We already have something similar here. TRRServer is a basic http2 server that only returns DNS response. We can use the same mechanism to create a generic server.