* 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
This makes it easier to make "standard" caddy builds, since you'll only
need to add a single import to get all of Caddy's standard modules.
There is a package for all of Caddy's standard modules (modules/standard)
and a package for the HTTP app's standard modules only
(modules/caddyhttp/standard).
We still need to decide which of these, if not all of them, should be
kept in the standard build. Those which aren't should be moved out of
this repo. See #2780.
