Swagger changes for Iot Hub (#12218)

* Revert swagger back to what is currently deployed

This swagger should never be hand edited. We can update it only when service accepts the changes

* Add composite swagger file with all suggested changes for service to make

read only, required params, and comment refactors. OperationId changes will go in here, too

* Regenerate PL with the currently deployed swagger

Author: timtay-microsoft