Add 'attachments_basic_api' test case. Covers basic api of the attachments package: 'attachments::attach', 'attachments::unattach', 'attachments::get_all_attachments', 'attachments::get_attachments' and 'attachments::toggle_approved'
just avoid tilde substitution, do not perform sanitizingsanitizing can lead to file name clashes in case the nameswithout tilde exists, and they are OS specific. The intentionof "ad_file" is just to be a tilde-proof "file" replacement