refactor: 2 improvements across 2 files

- UI/UX: Missing focus indicators on custom interactive elements
- UI/UX: Missing skip-to-content link for keyboard navigation

Signed-off-by: tomaioo <203048277+tomaioo@users.noreply.github.com>

Author: tomaioo

themes/arm-design-system-hugo-theme/layouts/partials/filter-search-sort/closed-expansion.html

@@ -37,7 +37,7 @@
                 <!-- Radio buttons -->
                 {{if eq $input_type "radio"}}
                     <div class="form-group ads-radio-style">
-                        <input type="radio" class="tag-{{$name | urlize}} group-{{$group_name}}" data-urlized-name="{{$name | urlize}}" name="{{$group_name}}" onchange="filterHandler_radio_LearningPaths(this)"></input>
+                        <input type="radio" id="{{$name | urlize}}" class="tag-{{$name | urlize}} group-{{$group_name}}" data-urlized-name="{{$name | urlize}}" name="{{$group_name}}" onchange="filterHandler_radio_LearningPaths(this)"></input>
                         <label for="{{$name | urlize}}">{{$name}}</label>
                     </div>
                 <!-- Checkboxes -->