[Compute] VMSS Redeploy and PerformMaintenance feature

[hyonholee]

Cmdlet design review:

https://github.com/Azure/azure-powershell-cmdlet-review-pr/issues/32

Description

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate change log has been updated
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • the changes have gone through a cmdlet design review
  • the cmdlet markdown files were generated using the platyPS module

[cormacpayne]

On-demand: https://azuresdkci.westus2.cloudapp.azure.com/job/powershell-demand/754/