docker: add Traefik support

USE_FOREIGN_CERT_MANAGER existed in compose/example.env but was never
read by any code. This wires it up end-to-end based on PR 662.

- Preliminarily add config options for this, and skip AcmetoolDeployer if
set.
- Add Traefik integration in docker/docker-compose-traefik.yaml, with
  traefik-certs-dumper
- post-hook.sh creates fullchain/privkey symlinks for chatmail
- Chatmail container uses ports 25/143/465/587/993 directly, Traefik
  handles 80/443
- docker/traefik/ contains config.yaml and dynamic configs
- docker/example-traefik.env for the Traefik setup
- rename USE_FOREIGN_CERT_MANAGER to CHATMAIL_NOACME

chatmaild/src/chatmaild/config.py

@@ -44,6 +44,7 @@ class Config:
         )
         self.mtail_address = params.get("mtail_address")
         self.disable_ipv6 = params.get("disable_ipv6", "false").lower() == "true"
+        self.noacme = os.environ.get("CHATMAIL_NOACME", "").lower() == "true"
         self.addr_v4 = os.environ.get("CHATMAIL_ADDR_V4", "")
         self.addr_v6 = os.environ.get("CHATMAIL_ADDR_V6", "")
         self.acme_email = params.get("acme_email", "")

chatmaild/src/chatmaild/ini/chatmail.ini.f

@@ -66,6 +66,7 @@ postfix_reinject_port_incoming = 10026
 # if set to "True" IPv6 is disabled
 disable_ipv6 = False
 
+
 # Your email adress, which will be used in acmetool to manage Let's Encrypt SSL certificates
 acme_email =