Merge KeyVault_preview to preview

[maddieclayton]

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

[maddieclayton]

on demand job here: https://azuresdkci.westus2.cloudapp.azure.com/view/PowerShell/job/powershell-demand/768/

[schaabs]

LGTM. After this is merged into preview it will it get merged to master for the build release?

[maddieclayton]

@schaabs Yes, it will first go to the release branch for //build, where it will be released with the rest of the modules, and then merged to master.

[RandalliLama]

@maddieclayton If @schaabs is happy then I am happy.