Take app_id in a URL fragment and fill that as the default selected app in
create backup form. This URL can be used in apps to create a backup link.
Tests:
- Visit /plinth/sys/backups/create/bepasty/. Only bepasty app will be selected.
- Visit /plinth/sys/backups/create/foo/. No apps are selected.
- Visit /plinth/sys/backups/create/. All apps are selected.
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>