Fix: enable stable Drupal OIDC support and PHP 8.2 base image

- Switched Drupal base image to PHP 8.2 for compatibility with openid_connect 2.x
- Added mariadb-client to container to allow Drush to drop tables
- Upgraded OIDC module from ^1 to ^2@beta for entity-based client configuration
- Replaced legacy client creation task with generic plugin-based entity creation
- Ensured /usr/local/bin is in PATH for www-data user
- Updated oidc.yml to explicitly use the generic plugin

References: https://chatgpt.com/share/6905cecc-8e3c-800f-849b-4041b6925381

roles/web-app-drupal/vars/oidc.yml

@@ -14,6 +14,7 @@ oidc_settings:
 oidc_client:
   id:                                "keycloak"
   label:                             "Keycloak"
+  plugin:                            "generic"   # use the built-in generic OIDC client plugin
   settings:
     client_id:                       "{{ OIDC.CLIENT.ID }}"
     client_secret:                   "{{ OIDC.CLIENT.SECRET }}"