ChefExtension support in the azure sdk toolkit

Contribution to the Azure SDK Toolkit from Chef - To support ChefExtension cmdlets.
Note - ClogenyTechnologies has a contract with Chef. We have signed the Microsoft CLA. This new PR has been created to accomodate the "rebase" after this repo had been restructured.
Original PR - https://github.com/Azure/azure-sdk-tools/pull/2576
It's up to you :-), but I think param set is easier to define and maintain.

It seems to me there can be 3 param sets:
1) ClientRb mandatory
2) ClientServerUrl & OrganizationName mandatory
2) ClientServerUrl & ValidationClientName mandatory