IMPL calls super in group_backend res_users compute_share

FIX applies pre-commit
IMPL adds test for share of backend user
FIX pre-commit pass
IMPL removes mail.activity.mixin from dummy model because it is not needed for the test
IMPL renames and divide the base_group_backend into 2 groups one that provide the basic rights and another that allow login in the app
IMPL changes backend ui users to a user type
FIX pre-commit pass
FIX removes useless imports
FIX adds share to group_backend_ui_users
IMPL adds mail_channel to access rights
FIX tests now working
FIX pre-commit pass

base_group_backend/demo/backend_dummy_model.xml

@@ -1,13 +1,12 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<odoo>
-
+<odoo noupdate="1">
     <record id="backend_dummy_model_tree_view" model="ir.ui.view">
         <field name="name">Backend dummy tree view</field>
         <field name="model">backend.dummy.model</field>
         <field name="arch" type="xml">
             <tree create="false" delete="false">
                 <field name="my_value" />
-                <field name="my_other_value" />
+                <field name="my_other_value" groups="base.group_user" />
             </tree>
         </field>
     </record>
@@ -24,20 +23,20 @@
         id="menu_dummy_root"
         name="Dummy"
         sequence="100"
-        groups="group_backend,base.group_user"
+        groups="group_backend_ui_users,base.group_user"
     />
     <menuitem
         id="menu_dummy_menu"
         name="Dummy"
         sequence="10"
-        groups="group_backend,base.group_user"
+        groups="group_backend_ui_users,base.group_user"
         parent="menu_dummy_root"
     />
     <menuitem
         id="menu_dummy_list"
         name="Dummy list"
         sequence="100"
-        groups="group_backend,base.group_user"
+        groups="group_backend_ui_users,base.group_user"
         parent="menu_dummy_root"
         action="action_dummy_list"
     />