Make listening on HTTPS port configurable (for Podman rootless)

[tonchikk]

Hi Team, https://github.com/jhpyle/docassemble/blob/5332f40cad442fed75a0a685ce996c30d4e78ecf/Docker/initialize.sh#L1378 Let's substitute 443 with ${HTTPSPORT:-443}

Same I've already done for unencrypted port:

$ vim env
$ cat env
PORT=9080
$ podman run --env-file=env -d -p 9080:9080 jhpyle/docassemble
3f563d9838b402d6a810af52694ca310f0314fe198616890a10f81e4af110941
$ podman ps
CONTAINER ID  IMAGE                                COMMAND               CREATED        STATUS        PORTS                   NAMES
3f563d9838b4  docker.io/jhpyle/docassemble:latest  /usr/bin/supervis...  7 seconds ago  Up 7 seconds  0.0.0.0:9080->9080/tcp  relaxed_darwin