[FIX] project: fix task navigation in portal project

This commit purpose is to fix the navigation in the project portal. When
a project is shared, the user can access all tasks of the project
from the project portal page, but when he select one task, he can not navigate from one task to another with
the previous and next button on the right of the header.

the commit :

 * fix the previous and next button of the task page. When a task is
reached by pressing one of these buttons, the navigation is not
interrupted and the user can navigate through all the tasks of the
project without having to go back to the project page

task-3032785

closes odoo/odoo#103736

Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>

addons/project/controllers/portal.py

@@ -248,7 +248,22 @@ class ProjectCustomerPortal(CustomerPortal):
             'user': request.env.user,
             'project_accessible': project_accessible,
         }
-        return self._get_page_view_values(task, access_token, values, history, False, **kwargs)
+
+        values = self._get_page_view_values(task, access_token, values, history, False, **kwargs)
+        if project:
+            history = request.session.get('my_project_tasks_history', [])
+            try:
+                current_task_index = history.index(task.id)
+            except ValueError:
+                return values
+
+            total_task = len(history)
+            task_url = f"{task.project_id.access_url}/task/%s?model=project.project&res_id={values['user'].id}&access_token={access_token}"
+
+            values['prev_record'] = current_task_index != 0 and task_url % history[current_task_index - 1]
+            values['next_record'] = current_task_index < total_task - 1 and task_url % history[current_task_index + 1]
+
+        return values
 
     def _task_get_searchbar_sortings(self):
         return {