Fix icons in the main menu

MDL-82210 (Add support to Font Awesome families) changed the
core/pix_icon template and removed the ‘fa’ class from the <i> element
in order to support different Font Awesome families.  This class is
instead added via \core\output\icon_system_fontawesome::add_family in
\core\output\icon_system_fontawesome::get_icon_name_map when no family
is set. However, since this theme overrides this method, the ‘fa’
class was never added to the additional icons of this theme. We
therefore set the ‘fa-solid’ family for all our additional icons.

Author: dlmsr

classes/output/icon_system_fontawesome.php

@@ -45,25 +45,25 @@ public function get_core_icon_map() {
         $iconmap = parent::get_core_icon_map();
 
         $override = [
-                'core:i/briefcase' => 'fa-briefcase',
-                'core:i/cogs' => 'fa-cogs',
-                'core:i/graduation-cap' => 'fa-graduation-cap',
-                'core:i/navigationbranch' => 'fa-wrench',
-                'core:i/navigationitem' => 'fa-angle-double-right',
-                'core:i/book' => 'fa-book',
-                'core:i/trophy' => 'fa-trophy',
-                'core:i/key' => 'fa-key',
-                'core:i/comment' => 'fa-comment',
-                'core:i/rss-square' => 'fa-rss-square',
-                'core:i/hidden' => 'fa-eye-slash',
-                'core:i/list' => 'fa-list',
-                'core:i/logout' => 'fa-sign-out',
-                'core:i/help' => 'fa-question-circle',
-                'core:i/hamburger' => 'fa-bars',
-                'core:i/sun' => 'fa-sun-o',
-                'core:i/moon' => 'fa-moon-o',
-                'core:i/magic' => 'fa-magic',
-                'core:i/theme' => 'fa-paint-brush',
+            'core:i/briefcase' => 'fa-solid fa-briefcase',
+            'core:i/cogs' => 'fa-solid fa-cogs',
+            'core:i/graduation-cap' => 'fa-solid fa-graduation-cap',
+            'core:i/navigationbranch' => 'fa-solid fa-wrench',
+            'core:i/navigationitem' => 'fa-solid fa-angle-double-right',
+            'core:i/book' => 'fa-solid fa-book',
+            'core:i/trophy' => 'fa-solid fa-trophy',
+            'core:i/key' => 'fa-solid fa-key',
+            'core:i/comment' => 'fa-solid fa-comment',
+            'core:i/rss-square' => 'fa-solid fa-rss-square',
+            'core:i/hidden' => 'fa-solid fa-eye-slash',
+            'core:i/list' => 'fa-solid fa-list',
+            'core:i/logout' => 'fa-solid fa-sign-out',
+            'core:i/help' => 'fa-solid fa-question-circle',
+            'core:i/hamburger' => 'fa-solid fa-bars',
+            'core:i/sun' => 'fa-solid fa-sun-o',
+            'core:i/moon' => 'fa-solid fa-moon-o',
+            'core:i/magic' => 'fa-solid fa-magic',
+            'core:i/theme' => 'fa-solid fa-paint-brush',
         ];
 
         return array_merge($iconmap, $override);