Replace PTE with supported alternative for the Operator Test Tool

PTE relies on an old unsupported version of the node SDK. The Operator Test tool relies on PTE to do admin (such as channel creation) as well as drive business logic for test purposes.

With the availability of the new gateway api and this will be the recommended api for client business applications we should replace the need to drive transactions with the new thin Go SDK.

For operational requirements we only have the osnadmin and peer cli commands to rely on. The Operator Test Tool already has some support for using the cli to perform operational activities, we need to look extend this.