[IMP]: point_of_sale: added `pos_categ_id` in the `group_by` filter of product search

Allowing user to group by the POS Product Category is more relevant

Task ID: 2419637

addons/point_of_sale/views/product_view.xml

@@ -8,6 +8,9 @@
             <filter name="filter_to_sell" position="before">
                <filter name="filter_to_availabe_pos" string="Available in POS" domain="[('available_in_pos', '=', True)]"/>
             </filter>
+            <filter name="categ_id" position="after">
+                <filter string="POS Product Category" name="pos_categ_id" context="{'group_by':'pos_categ_id'}"/>
+            </filter>
         </field>
     </record>