Return subscription name when creating resource group

**Is your feature request related to a problem? Please describe.**
I'm on many subscriptions and I don't have all the Guids memorized. When I create a resource group, I want to immediately be able to know, visually or programmatically, which subscription it was created on.

**Describe the solution you'd like**
Result of `az group create` returns subscription name, along with id.

**Describe alternatives you've considered**
The alternative is to hold the subscription in memory or ask for it after creating the subscription. These are both extraneous steps.

**Additional context**
Please think of the customer in terms of more information, instead of less, returned in the result.