Refactor elimination feature and improve backoffice usability

This commit introduces a refactored EliminationFactory for better modularity, updates the elimination preparation process, and adds functionality to view eliminations. Backoffice templates and forms have been reorganized, minor translations were corrected, and additional assets like styles and flashes were included for enhanced user experience.

templates/backoffice/registration/register.html.twig

@@ -0,0 +1,17 @@
+{% extends 'backoffice/base.html.twig' %}
+{% block title %}{{ 'Register'|trans }}{% endblock %}
+
+{% block body %}
+    <h3>{{ 'Register'|trans }}</h3>
+
+    {{ form_errors(registrationForm) }}
+
+    {{ form_start(registrationForm) }}
+    {{ form_row(registrationForm.email) }}
+    {{ form_row(registrationForm.plainPassword) }}
+
+    <button type="submit" class="btn btn-primary">Register</button>
+    <a href="{{ path('app_login_login') }}" class="btn btn-link">{{ 'Already have an account? Log in'|trans }}</a>
+
+    {{ form_end(registrationForm) }}
+{% endblock %}