Support Multi-Factor Authentication

[tdashworth]

There is a current known limitation to signing in with MFA as documented here. This has been solved for EasyRepro which we could reuse?

PR implementing MFA: microsoft/EasyRepro#735

[jaa2261]

Has there been any progress on this? Virtually all of our clients now use MFA so this is essentially killing off our ability to run the tests unless someone has a good workaround.