[FIX] crm: Prevent to select non-customer on lead quick creation

Purpose
=======

If you create an opp from the kanban you can select any contact (even if not marked "customer")

If you try to add a "non-customer" for the same field from the form view you cannot.

Specification
=============

Apply the same behavior than on the form view.

addons/crm/views/crm_lead_views.xml

@@ -203,7 +203,7 @@
                         <group>
                             <group>
                                 <field name="name" string="Opportunity Title" placeholder="e.g. Customer Deal"/>
-                                <field name="partner_id"/>
+                                <field name="partner_id" domain="[('customer', '=', True)]" context="{'search_default_customer': 1}"/>
                                 <field name="email_from" invisible="1"/>
                                 <field name="phone" invisible="1"/>
                                 <label for="planned_revenue"/>