[FIX] website_slides: properly display muted text in full-screen

Since a refactoring of the handling of the color system and the way the text
muted is handled, the text-muted isn't visible on the full-screen mode of a
course. That is becuase text-muted is based on the font color set for the body,
which in this case is quite similar to the background of left panel in
full-screen course content.

This commit fixes the issue by using `text-600` class that is suited for this
scenario (the background color is fixed here irrespective of the color-palette,
and so should be muted text-color) instead of `text-muted` for the left panel
of full-screen course content.

taskId - 2346013
closes #59390

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

addons/website_slides/views/website_slides_templates_lesson_fullscreen.xml

@@ -113,8 +113,9 @@
                         </a>
                         <span t-else="" class="d-block pt-1" href="#">
                             <div class="d-flex ">
+                                <t t-set="icon_class" t-value="'mr-2 text-600'"/>
                                 <t t-call="website_slides.slide_icon"/>
-                                <div class="o_wslides_fs_slide_name  text-muted" t-esc="slide.name"/>
+                                <div class="o_wslides_fs_slide_name text-600" t-esc="slide.name"/>
                             </div>
                         </span>
                         <ul class="list-unstyled w-100 pt-2 small" t-if="slide.link_ids or slide.slide_resource_ids or (slide.question_ids and not slide.slide_type =='quiz')" >
@@ -122,7 +123,7 @@
                                 <a t-if="can_access" class="o_wslides_fs_slide_link" t-att-href="link.link" target="_blank">
                                     <i class="fa fa-link mr-2"/><span t-esc="link.name"/>
                                 </a>
-                                <span t-else="" class="o_wslides_fs_slide_link text-muted">
+                                <span t-else="" class="o_wslides_fs_slide_link text-600">
                                     <i class="fa fa-link mr-2"/><span t-esc="link.name"/>
                                 </span>
                             </li>
@@ -153,7 +154,7 @@
                                 <a t-if="can_access" class="o_wslides_fs_slide_quiz" href="#" t-att-index="i">
                                     <i class="fa fa-flag-checkered text-warning mr-2"/>Quiz
                                 </a>
-                                <span t-else="" class="text-muted">
+                                <span t-else="" class="text-600">
                                     <i class="fa fa-flag-checkered text-warning mr-2"/>Quiz
                                 </span>
                             </li>