Fixed accessibility issues on AccessControlFormContainerComponent

- Replaced invisible label in AccessControlArrayFormComponent that was only used for styling with span
- Fixed radio buttons not being part of a fieldset
- Fixed empty table header

src/app/shared/object-select/collection-select/collection-select.component.html

@@ -11,7 +11,7 @@
       <table id="collection-select" class="table table-striped table-hover">
         <thead>
           <tr>
-            <th aria-hidden="true"></th>
+            <th><span class="sr-only">{{'collection.select.table.selected' | translate}}</span></th>
             <th scope="col">{{'collection.select.table.title' | translate}}</th>
           </tr>
         </thead>