refactor: make Authelia user management scalable

- Remove envsubst complexity for password hashes
- Keep users_database.yml only on server (not in git)
- Add users_database.yml to .gitignore
- Update users_database.template.yml with multi-user examples
- Configure Authelia to watch users_database.yml for changes
- Users can now be added/removed by editing the file on server
- Supports unlimited users without code changes

net/authelia/configuration.yml

@@ -41,7 +41,8 @@ authentication_backend:
     disable: false
   refresh_interval: 5m
   file:
-    path: /config/users_database.yml
+    path: /etc/authelia/users_database.yml
+    watch: true
     password:
       algorithm: argon2
       argon2: