Support Cloud Shell VNETs in secondary regions

[maertendMSFT]

Evaluating support for secondary regions. More info on VNET support can be found in our documentation.

This change would add support for secondary regions where Azure Container Instances is present.

[DXPetti]

Currently, my customers cannot consume Cloud Shell for a number of reasons:

1. Compute is located out of the region
2. Public connectivity to resources is required (which CS VNets w/ Relay resolves)
3. Control around the session, specifically copy/paste and upload/download is not available.

Adding my support for this idea as it solves one problem

[rowanmoul]

Is this part of the "Improving the configuration options of the VNET scenario." bullet point from the 2023 road map? I would like to be able to use cloud shell to run things like terraform more securely, but I would like to keep the storage account in my own country for data residency reasons.