Add flag to login to generate non-persisted keys

[BobWall23]

Use Case: you are generating keys to put on a machine where you can't log in and run a web browser to do the auth0 flow. Instead, run ironhide on a machine where you do have a browser, and might already have keys generated, but run a genkeys command that causes IronHide to ignore the existing keys, generate a new set of keys, and just print the JSON to stdout. You can cut and paste it, redirect to a file, or pipe into an SSH that cats the input into a file on the remote machine.

[ernieturner]

Probably makes more sense to have this be a separate command now that I think about it. Something like ironhide genkeys or something. No real reason to overload the login command.

[BobWall23]

In retrospect, that seems pretty obvious. Updated title and description.

[ernieturner]

This would take more work than expected because we need to redo the Auth0 login flow and ask the user for their account password. Possible, but should include a bit of refactoring to make Auth0 flow more generic so it can be shared between login and genkeys. Repointing to 5.