[FIX] mail: activity popup is outside the screen

Before this commit, the popup activity in kanban was rendered using
the position of the button. So the left popup was nearly in the center
of the screen but the width is too large to be contained on the screen.

After this commit, in mobile, the popup activity in kanban will be
placed on the left of the button to avoid to go outside of the viewport.

Steps to reproduce:
* Go to sale app (in mobile)
* Click on the activity button of a kanban card (clock icon) BUG

Task ID: 2198429

closes odoo/odoo#45860

X-original-commit: 392c8a57df798d92b8be73d743b690891cf2fda2
Signed-off-by: Pierre Paridans <pparidans@users.noreply.github.com>

addons/mail/static/src/js/activity.js

@@ -5,6 +5,7 @@ var mailUtils = require('mail.utils');
 
 var AbstractField = require('web.AbstractField');
 var BasicModel = require('web.BasicModel');
+var config = require('web.config');
 var core = require('web.core');
 var field_registry = require('web.field_registry');
 var session = require('web.session');
@@ -711,7 +712,9 @@ var KanbanActivity = BasicActivity.extend({
      */
     _renderDropdown: function () {
         var self = this;
-        this.$('.o_activity').html(QWeb.render('mail.KanbanActivityLoading'));
+        this.$('.o_activity')
+            .toggleClass('dropdown-menu-right', config.device.isMobile)
+            .html(QWeb.render('mail.KanbanActivityLoading'));
         return _readActivities(this, this.value.res_ids).then(function (activities) {
             activities = setFileUploadID(activities);
             self.$('.o_activity').html(QWeb.render('mail.KanbanActivityDropdown', {