[FIX] website_slides: allow portal users to rate

PURPOSE

Test frontend and UI tools of eLearning.

SPECIFICATIONS

Portal users cannot post reviews as they have no write right on channels.
When trying to post a review on a channel this leads to a 403.

In this commit we correctly propagate channel access token to the composer
in order to allow rating.

LINKS

Task ID 1937768

addons/website_slides/views/website_slides_templates_course.xml

@@ -144,6 +144,7 @@
                                     <t t-set="rating_avg" t-value="rating_avg"/>
                                     <t t-set="rating_total" t-value="rating_count"/>
                                     <t t-set="object" t-value="channel"/>
+                                    <t t-set="token" t-value="channel.access_token"/>
                                     <t t-set="hash" t-value="message_post_hash"/>
                                     <t t-set="pid" t-value="message_post_pid"/>
                                     <t t-set="default_message_id" t-value="last_message_id"/>