CLI commands for SharedVmExtension and SharedVmExtensionVersion

**Resource Provider**
What is the Azure resource provider your feature is part of?
Microsoft.Compute

**Description of Feature or Work Requested**
Currently the VM extensions are published using RDFE APIs and are replicated within RDFE itself. Since the RDFE is in deprecation phase, we need a new set of APIs for extension publishing. These new APIs are added in CAPS which will be called by extension publishers.

There are two sets of APIs for SharedVmExtension and SharedVmExtensionVersion respectively.

**Minimum API Version Required**
What is the minimum API version of your service required to implement your feature?
2019-12-01

**Swagger Link**
https://github.com/Azure/azure-rest-api-specs-pr/blob/Azure-Compute/specification/compute/resource-manager/Microsoft.Compute/stable/2019-12-01/extension.json

**Target Date**
11/29/2019