* pki: Initial commit of PKI app (WIP) (see #2502 and #3021)

* pki: Ability to use root/intermediates, and sign with root

* pki: Fix benign misnamings left over from copy+paste

* pki: Only install root if not already trusted

* Make HTTPS port the default; all names use auto-HTTPS; bug fixes

* Fix build - what happened to our CI tests??

* Fix go.mod