Microsoft delivered vendor approval workflow with October release.
Please include all fields on Vendors form in this functionality and also let users to configure workflow approval requirements for new vendors as well.

For new vendors workflow, a simple solution might be:
1. Adding a checkbox in AP parameters to set all new vendors to On hold = All.
2. Setting "Current" value in change proposals to All, "Proposed value" to "No"
3. Approval of workflow updates vendor on hold status to "No".