Add option to just output aws console URL instead of redirecting

[limed]

Sometimes we have to open multiple AWS consoles (we do this using container tabs) so on top of the maws -w command can we get an additional flag like --url for example that will print out the AWS console URL for federated users once we have done the SSO dance.

See: https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_providers_enable-console-custom-url.html

[gene1wood]

I was looking at #213 but haven't found a perfect solution yet.