LPS-33805 Removing path parameter from StagedModelDataHandler interface

Hey Mike,

This is one PR I was talking about. The purpose of the whole change is to get rid of the path parameter from the interface and the base classes.

I'd like to clean it out because it was only introduced to be able to pass it on to the createServiceContext method and I wouldn't force the users of this API to produce values to pass to the framework if the framework can produce that value as well.

I'm planning to remove the Element parameters as well soon.

Thanks,

Máté

cc: @KocsisDaniel