issue: DB Error #1062

This addresses a long-time issue of the famous `DB Error #1062` when
uploading an Inline File to a Draft. The issue is that the system does not
check if an Attachment record exists before creating a new one. We create a
new Attachment record, we go to save it, and the system errors out because
that record already exists. This adds a check to see if the Attachment
record already exists and if so we use that instead of creating a new one.