Support for IPv6 Global Reach CRUD operations

[tanuballa]

Is your feature request related to a problem? Please describe.
This feature request is for CLI support for a new ExpressRoute feature that brings IPv6 support to our existing Global Reach offering. With IPv6 support, customers will be able to create/update/delete new Global Reach connections with dual-stack subnets, as well as update existing IPv4 Global Reach connections to add an IPv6 config. This enables users to make progress on their dual-stack or IPv6 journey with Azure and on-premises networks.

Describe the solution you'd like
We would like to be able to add an IPv6 config to a Global Reach connection, and delete an IPv6 config from a Global Reach connection.

Describe alternatives you've considered
We already have PowerShell support, with the following commands:

Adding an IPv6 config to a Global Reach connection:
Add-AzExpressRouteCircuitConnectionConfig -Name 'Your_connection_name' -ExpressRouteCircuit $ckt_1 -PeerExpressRouteCircuitPeering $ckt_2.Peerings[0].Id -AddressPrefix '.../29' -AddressPrefixType IPv6

Deleting an IPv6 config from a Global Reach connection:
Remove-AzExpressRouteCircuitConnectionConfig -Name "Your_connection_name" -ExpressRouteCircuit $ckt_1 -AddressPrefixType IPv6

Additional context
Minimum API Version: 2019-08-01
Swagger: Azure/azure-rest-api-specs#10325
Feature Status: Not released, can test by working with Tanu Balla (taballa) to enable feature flags on subscription
ETA: Aiming for Public Preview by Ignite Nov21

[yonzhan]

network

[jsntcy]

Synced with @tanuballa in email, this feature will be released on Dec 7.