webapp/templates/layout: Fix deposit moderation view integration
Test in template file must be splitted in two: one to check if the swh.web.deposit application is installed, another one to check user permissions.
An error was raised otherwise when swh.web.deposit is not in installed application and when admin user logs in.
Related to #4398 (closed)
Migrated from D8394 (view on Phabricator)