[FIX] portal: show line return in chatter message

In the frontend only plaintext is saved without any javascript fiddling
so in the controller it should be adapted to be saved.

With this change, the behavior is more similar to backend chatter which
sends html (processed by javascript) to the server.

opw-1817918
closes #23706

addons/portal/controllers/mail.py

@@ -6,7 +6,7 @@ from werkzeug.exceptions import NotFound, Forbidden
 from odoo import http
 from odoo.http import request
 from odoo.osv import expression
-from odoo.tools import consteq
+from odoo.tools import consteq, plaintext2html
 
 
 def _has_token_access(res_model, res_id, token=''):
@@ -59,6 +59,8 @@ class PortalChatter(http.Controller):
     def portal_chatter_post(self, res_model, res_id, message, **kw):
         url = request.httprequest.referrer
         if message:
+            # message is received in plaintext and saved in html
+            message = plaintext2html(message)
             _message_post_helper(res_model, int(res_id), message, **kw)
             url = url + "#discussion"
         return request.redirect(url)