FQDN support for LocalNetworkGateway and VpnSiteLink

[aknandagit]

Description

Updated the cmdlets New-AzVpnSiteLink and New-AzLocalNetworkGateway with a new parameter set that takes Fqdn instead of IpAddress.

Checklist

• [ X] I have read the Submitting Changes section of CONTRIBUTING.md
• [ X] The title of the PR is clear and informative
• [ X] The appropriate ChangeLog.md file(s) has been updated:
  • For any service, the ChangeLog.md file can be found at src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md
  • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header -- no new version header should be added
• [ X] The PR does not introduce breaking changes
• [X ] If applicable, the changes made in the PR have proper test coverage
• [ X] For public API changes to cmdlets:
  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
  • [ X] the markdown help files have been regenerated using the commands listed here

[adxsdkps]

Can one of the admins verify this patch?

[msJinLei]

@aknandagit Please fix the test failure.

[msJinLei]

Move to new PR #11482