15f7368 Add function to get user by username to fas module

Authored and Committed by zlopez 2 years ago
    Add function to get user by username to fas module
    
    `scm_request_processor` needs to get user by username from FAS. This commits
    adds that function.
    
    Signed-off-by: Michal Konečný <mkonecny@redhat.com>