[IMP] website_slides: make course picture editable in frontend

Purpose of this commit is to allow website designers to change course images
directly from front-end.

Task 2026846

addons/website_slides/static/src/scss/website_slides.scss

@@ -21,12 +21,9 @@ $o-wslides-fs-side-width: 300px;
 
 .o_wslides_course_pict {
     @include size(100%);
-    padding-top: 30%;
-    background-size: cover;
-    background-position: center;
+    object-fit: cover;
 
     @include media-breakpoint-up(md)  {
-        padding-top: 70%;
         border: 1px solid darken(#875A7B, 10%);
         border-bottom-width: 0;
     }

addons/website_slides/views/website_slides_templates_course.xml

@@ -119,8 +119,8 @@
                     <div class="row align-items-end align-items-md-stretch">
                         <!-- ==== Header Left ==== -->
                         <div class="col-12 col-md-4 col-lg-3">
-                            <div class="d-flex align-items-start justify-content-around h-100">
-                                <div class="o_wslides_course_pict d-inline-block mb-2 mt-3 my-md-0" t-attf-style="background-image: url(#{website.image_url(channel, 'image_1024')});" t-ignore="True"/>
+                            <div class="d-flex align-items-end justify-content-around h-100">
+                                <div t-field="channel.image_1920" t-options='{"widget": "image", "class": "o_wslides_course_pict d-inline-block mb-2 mt-3 my-md-0"}' class="h-100"/>
                             </div>
                         </div>