Feature request: Okta auth with MFA

[restfulhead]

Currently the Okta authentication backend asks for a username and password. It would be nice if it would also consider MFA.

Here's an example (in Java) of how such a MFA challenge could look like
https://github.com/oktadeveloper/okta-aws-cli-assume-role/blob/master/src/main/java/com/okta/tools/awscli.java#L789

[joaquinrinaudo-olx]

+1

[steve-jansen]

This issue can be closed thanks to #3653

[jefferai]

Will do.