feat(e2e): add data attributes for improved test stability

Add data-what and data-which attributes to key UI elements:
- Add back button attributes to return details and process components
- Add filter button attributes to the filter menu component
- Add sort button attributes for both desktop and mobile views
- Add result count element attributes for better selection
- Add attributes to search result items for identification
- Add attributes to loading spinners for state verification

These attributes improve E2E test stability by providing reliable selectors
that are not tied to styling or DOM structure changes.

Ref: #5052

libs/shared/filter/src/lib/menus/filter-menu/filter-menu-button.component.html

@@ -5,6 +5,7 @@
   (click)="toggle()"
   type="button"
   [class.active]="isIconButtonActive()"
+  data-what="filter-button"
 >
   <ng-icon name="isaActionFilter"></ng-icon>
 </button>

libs/shared/filter/src/lib/order-by/order-by-toolbar.component.html

@@ -7,6 +7,8 @@
       uiTextButton
       type="button"
       (click)="toggleOrderBy(orderBy)"
+      data-what="sort-button"
+      [attr.data-which]="orderBy.by"
     >
       <div>
         {{ orderBy.label }}