Add feature flag for full record fulfillment links

Why these changes are being introduced:

Initial usability testing suggested that the
'View full record' fulfillment links are not
frequently used. UXWS would like to hide this
feature for testing, and possibly bring it back
if users struggle to reach the records in
external systems.

Relevant ticket(s):

* [USE-253](https://mitlibraries.atlassian.net/browse/USE-253)

How this addresses that need:

This adds a `record_link` feature flag and hides
the full record fulfillment links behind it.

Side effects of this change:

If we decide to permanently remove these links,
we should remove the feature flag as well.

Author: jazairi

app/models/feature.rb

@@ -34,7 +34,7 @@
 class Feature
   # List of all valid features in the application
   VALID_FEATURES = %i[geodata boolean_picker simulate_search_latency tab_primo_all tab_timdex_all
-                      tab_timdex_alma].freeze
+                      tab_timdex_alma record_link].freeze
 
   # Check if a feature is enabled by name
   #

app/views/search/_result.html.erb

@@ -56,8 +56,10 @@
       <%= render partial: 'search/highlights', locals: { result: result } %>
     </div>
 
-    <div class="result-get">
-      <%= view_record(result) %>
-    </div>
+    <% if Feature.enabled?(:record_link) %>
+      <div class="result-get">
+        <%= view_record(result) %>
+      </div>
+    <% end %>
   </div>
 </li>

app/views/search/_result_primo.html.erb

@@ -63,7 +63,9 @@
       <% if result[:links].present? %>
         <% result[:links].each do |link| %>
           <% if link['kind'].downcase == 'full record' %>
-            <%= view_record(link) %>
+            <% if Feature.enabled?(:record_link) %>
+              <%= link_to 'View full record', link['url'], class: 'button' %>
+            <% end %>
           <% else %>
             <%= link_to link['kind'].titleize, link['url'], class: 'button' %>
           <% end %>