Add support for supplementary environment values in Chill configuration

Introduced `supplementary_environment_values` in Chill defaults and updated `env_file.env` template to dynamically inject custom environment variables. Added placeholder `docker_secrets` for future secrets management.

defaults/main.yml

@@ -13,6 +13,8 @@ traefik_image_traefik: "traefik:v3.2"
 # to install or not traefik as front-end
 traefik_install: true
 
+docker_secrets: []
+
 # default chill config for each environment
 default_chill:
   chill_environment: main_env
@@ -29,6 +31,8 @@ default_chill:
     - 10.0.0.0/8
     - 172.16.0.0/12
   chill_config:
+    # supplementary environment values to set in the in the env file
+    supplementary_environment_values: {}
     trusted_hosts: 'devpms.samusocial.be '
     database_host: '172.17.17.71'
     database_port: '5432'