add postgres support for mx-puppet-* with fallback to sqlite in role and migration notice

roles/matrix-bridge-mx-puppet-discord/templates/config.yaml.j2

@@ -100,15 +100,18 @@ namePatterns:
   group: :name
 
 database:
+{% if matrix_mx_puppet_slack_discord_database_engine == 'sqlite' %}
+  # Use SQLite3 as a database backend
+  # The name of the database file
+  filename: /data/database.db
+{% else %}
   # Use Postgres as a database backend
   # If set, will be used instead of SQLite3
   # Connection string to connect to the Postgres instance
   # with username "user", password "pass", host "localhost" and database name "dbname".
   # Modify each value as necessary
-  connString: "postgres://matrix_puppet_discord:{{ matrix_additional_databases | selectattr('name', 'equalto', 'matrix_puppet_discord') | map(attribute='pass') | first }}@{{ matrix_postgres_connection_hostname }}/matrix_puppet_discord?sslmode=disable"
-  # Use SQLite3 as a database backend
-  # The name of the database file
-  #filename: /data/database.db
+  connString: {{ matrix_mx_puppet_discord_database_connString|to_json }}
+{% endif %}
 
 logging:
   # Log level of console output