az ad app should be able to set oauth2AllowImplicitFlow=true

[gavinbarron]

To provision or update an AD App Registration which allows the OAuth2 Implicit flow you must either use the PowerShell tools or open the portal to complete this configuration step.

It would be good to have a true cross platform means of doing this with the az ad app commands

[yugangw-msft]

I added yesterday through #5852