cmdeploy: prepare chatmaild/cmdeploy changes for Docker support

- chatmaild:
  - basedeploy.py: Add has_systemd() guard. During Docker image builds
    there's no running systemd, so deployers that query SystemdEnabled
    facts would crash; this change might also be helpful for non-systemd
    platforms.
- cmdeploy:
  - cmdeploy.py:
    - when deploying to @docker, auto-set CHATMAIL_NOPORTCHECK and
      CHATMAIL_NOSYSCTL since neither makes sense inside a container
    - --config default now reads CHATMAIL_INI env var, so Docker
      entrypoints can point to a mounted ini without CLI flags.
  - deployers.py:
    - skip port check / CHATMAIL_NOPORTCHECK
    - skip echobot systemd cleanup w/ has_systemd
  - dovecot/deployer.py:
    - Guard sysctl writes behind CHATMAIL_NOSYSCTL
    - invert dovecot install check so it works without systemd
  - sshexec.py: Add __call__ to LocalExec so cmdeploy status works with
    @local target. Without it, cmdeploy status tried to call the
    executor directly and got TypeError.

Consolidated from j4n/docker branch commits (selection):
- 8953fde feat(cmdeploy): read CHATMAIL_INI env var for default --config path
- 81d7782 fix(cmdeploy): add __call__ to LocalExec so status works with @local
- 8bba78e docker: disable port check if docker is running. fix #694
- 865b514 docker: replace config flags with env vars, drop docker param (instead of f26cb08)

Files: cmdeploy/src/cmdeploy/{basedeploy,cmdeploy,deployers,sshexec,dovecot/deployer}.py

Co-authored-by: Keonik1 <keonik.dev@gmail.com>
Co-authored-by: missytake <missytake@systemli.org>

cmdeploy/src/cmdeploy/deployers.py

@@ -599,6 +599,9 @@ def deploy_chatmail(config_path: Path, disable_mail: bool, website_only: bool) -
             # so don't complain during upgrade that moved it to port 402
             # and gave the port to nginx.
             (["acmetool", "nginx"], 80),
+            port_services.append(("acmetool", 80))
+        port_services += [
+            (["imap-login", "dovecot"], 143),
             ("nginx", 443),
             (["master", "smtpd"], 465),
             (["master", "smtpd"], 587),