Describe the feature or problem you’d like to solve

When using gh pr create and adding assignees, there's a filter interface to let you select a username, but no way to see real names. This is tricky when collaborating with people where you know their name, but not their github login.

Proposed solution

The list should include names as well as usernames for filtering, so you could type "John" and get a match for "jsmith John Smith".

Additional context

The web interface already behaves this way, so this enhancement reduces the feature gap between the two.