[IMP] website_slides: allow course to have prerequisites

This commit allows the course manager to add prerequisites
courses to a course so that the final user will be notified
on the frontend he has to take some courses before the one he
wants. He could however request access to the course and
take it without taking the prerequisites before if the access
has been granted.

Task-3213628

closes odoo/odoo#114710

Signed-off-by: Warnon Aurélien (awa) <awa@odoo.com>

addons/website_slides/data/slide_channel_demo.xml

@@ -42,6 +42,9 @@
     <record id="slide_channel_demo_2_gard2" model="slide.channel">
         <field name="name">Trees, Wood and Gardens</field>
         <field name="user_id" ref="base.user_demo"/>
+        <field name="prerequisite_channel_ids" eval="[(5, 0),
+                                                      (4, ref('website_slides.slide_channel_demo_0_gard_0')),
+                                                      (4, ref('website_slides.slide_channel_demo_1_gard1'))]"/>
         <field name="enroll">public</field>
         <field name="channel_type">documentation</field>
         <field name="allow_comment" eval="True"/>