Adding fieldset to address like named form inputs

In consultation with @Dananji and following the [guidance of W3.org][1],
this commit wraps the forms (or controls) that render the
[add_buttom partial][2].  I don't believe that I have access to the
accessibility testing software, so this is a bit of a stab in the dark.

Note, in some cases I render the fieldset as a direct child of the form,
in other cases, I render the fieldset as a container for the table used
to present the elements that render the add button partial.

This relates to work done in #4160 to address #3966.

[1]:https://www.w3.org/WAI/tutorials/forms/grouping/
[2]:https://github.com/samvera/hyrax/blob/d5aa2f9ca802fe670687bb4f7c14ad242c1bacf6/app/views/hyrax/batch_select/_add_button.html.erb#L2

app/views/hyrax/collections/_default_group.html.erb

@@ -1,3 +1,4 @@
+<fieldset>
 <table class="table table-striped">
   <caption class="sr-only"><%= t("hyrax.dashboard.my.sr.listing") %> <%= application_name %></caption>
   <thead>
@@ -20,3 +21,4 @@
   <% end %>
   </tbody>
 </table>
+</fieldset>

app/views/hyrax/dashboard/works/_default_group.html.erb

@@ -1,3 +1,4 @@
+<fieldset>
 <table class="table table-striped works-list">
   <caption class="sr-only"><%= t("hyrax.dashboard.my.sr.listing") %> <%= application_name %></caption>
   <thead>
@@ -18,3 +19,4 @@
   <% end %>
   </tbody>
 </table>
+</fieldset>

app/views/hyrax/leases/_list_expired_active_leases.html.erb

@@ -17,6 +17,7 @@
 <% else %>
 
   <%= form_tag leases_path, method: :patch do %>
+    <fieldset>
     <%= submit_tag t('.deactivate_selected'), class: 'btn btn-primary' %>
     <table class="leases table">
       <thead>
@@ -49,5 +50,5 @@
       </tbody>
     </table>
   <% end %>
-
+  </fieldset>
 <% end %>

app/views/hyrax/my/works/_default_group.html.erb

@@ -1,3 +1,4 @@
+<fieldset>
 <table class="table table-striped works-list">
   <caption class="sr-only"><%= t("hyrax.dashboard.my.sr.listing") %> <%= application_name %></caption>
   <thead>
@@ -16,3 +17,4 @@
   <% end %>
   </tbody>
 </table>
+</fieldset>