Include metadata regarding the provider of the FDC3 api

[donbasuno]

Enhancement Request

Use Case:

As a vendor or application developer I would be interested in knowing which container, service or desktop agent is providing the FDC3 functionality to my applications - for error handling, logging or just basic statistics. It would be specifically useful as we are seeing a number of proprietary implementations and browser extensions being developed.

For example:

//log fdc3 provider
console.log("FDC3 Provider Service: " + fdc3.provider);