frontend: more understandable permissions errors
    
    New format is:
    
        Something went wrong:
        Error: User 'praiskup' doesn't have access to the copr group 'maistra' (fas_name='maistra')
        Something went wrong:
        Error: You were authorized as 'praiskup' user without permissions to access projects of user 'frostyx'
    
    vs. the old variant:
    
        Something went wrong:
        Error: User 'praiskup' doesn't have access to group maistra(maistra)
        Something went wrong:
        Error: You were authorized as `praiskup' and don't have permissions to access project of `frostyx' user