Add installation via docker compose (MVP 1)

- Add markdown tabs blocks
- Fix [Issue 604](https://github.com/chatmail/relay/issues/604)
- Add `--skip-dns-check` argument to `cmdeploy run` command
- Add `--force` argument to `cmdeploy init` command
- Add startup for `fcgiwrap.service`
- Add extended check when installing `unbound.service`
- Add configuration parameters (`is_development_instance`, `use_foreign_cert_manager`, `acme_email`, `change_kernel_settings`, `fs_inotify_max_user_instances_and_watchers`)

docker/files/entrypoint.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+set -eo pipefail
+
+if [ "${USE_FOREIGN_CERT_MANAGER,,}" == "true" ]; then
+    if [ ! -f "$PATH_TO_SSL_CONTAINER/fullchain" ]; then
+        echo "Error: file '$PATH_TO_SSL_CONTAINER/fullchain' does not exist. Exiting..." > /dev/stderr
+        exit 1
+    fi
+    if [ ! -f "$PATH_TO_SSL_CONTAINER/privkey" ]; then
+        echo "Error: file '$PATH_TO_SSL_CONTAINER/privkey' does not exist. Exiting..." > /dev/stderr
+        exit 1
+    fi
+fi
+
+SETUP_CHATMAIL_SERVICE_PATH="${SETUP_CHATMAIL_SERVICE_PATH:-/lib/systemd/system/setup_chatmail.service}"
+
+env_vars=$(printenv | cut -d= -f1 | xargs)
+sed -i "s|<envs_list>|$env_vars|g" $SETUP_CHATMAIL_SERVICE_PATH
+
+exec /lib/systemd/systemd $@