Fabric connectors do not need to create gateway objects if context created by manager

[davidkel]

In the past for the fabric connector the manager would need a context to do things like install/instantiate chaincode, creat channels etc and thus the 1.4 non gateway connector needed to provide client instances.

Now with the 1.4 client non gateway implementation gone and only gateway implementations and the manager is not going to perform any interaction with fabric, we can now optimse the manager process when interacting with fabric. It always requests a context, but now for the manager process the fabric connector doesn't need to create gateway objects (it never needed to anyway as the gateway version didn't allow the manager ability to perform install/instantiate etc).

This allows for a performance improvement in caliper itself.

It will also facilitate not having to have a real network-config file for the manager process (when running with remote workers) which you can do with the 2.4 connector because although gateway objects are created they are lightweight and do no identity checking on connection (2.2 and 1.4 do so they fail if you don't have a real network-config file with valid identities)