feat: password reset (#179) (#186)

* feat: password reset via symfonycasts/reset-password-bundle (#179)

Implements the full password reset flow using the SymfonyCasts reset-password-bundle.

* ci: share base layer cache between dev and prod builds

* fix: use CSS form selector in tests instead of translated button text

* fix: translate missing validator string for reset password email field

* fix: translate reset password form labels via TranslatorInterface

* ci: override MAILER_DSN to null for PHPUnit so mailer host is not required

templates/reset_password/reset.html.twig

@@ -0,0 +1,12 @@
+{% extends 'backoffice/base.html.twig' %}
+
+{% block title %}Nieuw wachtwoord instellen{% endblock %}
+
+{% block body %}
+    <h3 class="mb-3">{{ 'Reset your password'|trans }}</h3>
+
+    {{ form_start(resetForm) }}
+    {{ form_row(resetForm.plainPassword) }}
+    <button class="btn btn-primary" type="submit">{{ 'Reset password'|trans }}</button>
+    {{ form_end(resetForm) }}
+{% endblock %}