support: sovereign cloud

[yugangw-msft]

This line by hard coding to public azure blocks authentication in sovereign clouds. Please fix it soon

//CC @marstr @rayluo

[rayluo]

Admittedly, sovereign cloud scenario wasn't tested. In fact, it wasn't in the picture when we developed that line 3 years ago. We will take a look into this.

By the way, how does CLI works with sovereign cloud using ADAL Python today? I thought ADAL Python and MSAL Python behave the same in this aspect.

[yugangw-msft]

No. ADAL works right now. You run "az cloud set -n AzureChinaCloud" and "az login" will work