R1:a83ba95445e1

Only display "Calendar" entry in user profile page menu on mobile when Calendar application is installed

Summary:
https://we.phorge.it/source/phorge/browse/master/src/view/page/PhabricatorStandardPageView.php$908 tries to "find some navigational menu items to create a mobile navigation menu from" but does not succeed too much it seems:
On a user profile page, that very code calls `buildApplicationMenu()` in `PhabricatorPeopleController` which calls `buildSideNavView()` in the same class.
This code…