Import roles command does not handle users with the same display name

[Vitor-Avila]

The import-roles command can be used to manage DARs based on a YAML file. In case there are two users with the same display name in the Workspace/Superset instance, it's not possible to specify/differentiate which one should be used in the DAR.

[vadivelselvaraj]

To be precise, the issue happens for users with the same first and last name though they have different usernames. The CLI could easily differentiate them using their usernames that are provided in the DAR YAML file.

On an unrelated note, a good PFR for the UI would be to add a (username) suffix to the names to help choose the right user.