Search failure obvious for user.

Before this patch, when a user searched something in the shop and no results were yielded, there was no clue that the problem might be the search query itself.

After this patch, this UX becomes more obvious:

- *(0 found)* appears next to search button.
- _No results found for **"search term"**_ appears clearly in the middle of the page.

This commit closes #14359

addons/website_sale/views/templates.xml

@@ -62,7 +62,7 @@
 
     <template id="search count" inherit_id="website.website_search_box" active="False" customize_show="True" name="Show # found">
         <xpath expr="//button[hasclass('oe_search_button')]" position="inside">
-            <span t-if='search and search_count' class='oe_search_found'> <small>(<t t-esc="search_count"/> found)</small></span>
+            <span t-if='search' class='oe_search_found'> <small>(<t t-esc="search_count"/> found)</small></span>
         </xpath>
     </template>
 
@@ -211,6 +211,11 @@
                             <t t-if="not bins">
                                 <div class="text-center text-muted oe_product">
                                     <h3 class="css_editable_display">No product defined.</h3>
+                                    <t t-if="search">
+                                        <p>
+                                            No results found for "<strong t-esc='search'/>".
+                                        </p>
+                                    </t>
                                     <p groups="sales_team.group_sale_manager">Click <i>'New'</i> in the top-right corner to create your first product.</p>
                                 </div>
                             </t>