Refactor E2E tests and configuration format

- Replaced `easymapping` configuration with `containers` for better maintainability and clarity.
- Introduced `DockerComposeFixture` class in `utils.py` to manage Docker Compose lifecycle and smart build strategy.
- Enhanced YAML-to-environment variable conversion in `ContainerEnv` for dynamic configuration support.
- Updated HAProxy configurations and test fixtures to reflect the new format.
- Improved test coverage for YAML parsing, environment variable handling, and HAProxy config generation.

docs/Plugins/deny-pages.md

@@ -74,15 +74,13 @@ spec:
 
 ```yaml
 # /etc/haproxy/static/config.yaml
-easymapping:
-  - host: example.com
-    port: 80
-    container: webapp:80
-    plugins:
-      - deny_pages
-    plugin_config:
+containers:
+  "example.com:80":
+    ip: ["webapp:80"]
+    plugins: [deny_pages]
+    plugin:
       deny_pages:
-        paths: /admin,/private,/debug
+        paths: [/admin, /private, /debug]
         status_code: 403
 ```