Support to Get IKE Security Associations on Virtual Network Gateway Connections

[abhi7860]

Description

Customers can now fetch IKE Security Associations for their Virtual Network Gateway Connections

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• 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
• 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:

  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)

    • https://github.com/Azure/azure-powershell-cmdlet-review-pr/issues/803

  • the markdown help files have been regenerated using the commands listed here

[isra-fel]

A few things missing in your PR:

• You are using some new API IVirtualNetworkGatewayConnectionsOperations.GetIkeSas() that is available in the SDK on network-august branch right now. Please check in your local SDKs (and any related changes) to unblock build
• You need tests to cover the new command

[isra-fel]

Hi @abhi7860 as @MikhailTryakhov 's PR #13927 already merged network-august branch to master, network-august branch became stale. Any later PR (including this one) merged into network-august won't be included in this release.
Please edit the base branch of your PR to release-2021-01-19 if you wish to catch this release

[isra-fel]

LGTM!