[StorageSync]: Add Environment extensions for static values

[markcowl]

Description

The StorageSync cmdlets depend on an environment-specific SPN (KailaniAppID) add the appropriate value to the environment extensions for built-in environments

• Add extension key/value pair for Global and US Government Clouds to AzureEnvironment extension properties in powershell-common repo.

• Update cmdlet code to use the extension value

Cost: 1

[ankushbindlish2]

https://github.com/Azure/azure-powershell-common/blob/master/src/Authentication.Abstractions/Extensions/AzureEnvironmentExtensions.cs