[IMP] crm_mail_plugin: store the HTML version of the email on the lead

Purpose
=======
In helpdesk_mail_plugin and project_mail_plugin we store the HTML
version of the email body on the description field.

But in CRM, we store the text version of the email, we want this
behavior to be consistent and we now store the HTML version of the
email on the lead.

Task-2518668

addons/crm_mail_plugin/controllers/crm_client.py

@@ -46,7 +46,7 @@ class CrmClient(http.Controller):
         record = request.env['crm.lead'].create({
             'name': html2plaintext(email_subject),
             'partner_id': partner_id,
-            'description': html2plaintext(email_body),
+            'description': email_body,
         })
 
         return {'lead_id': record.id}