private async Task ObrisiRolu(DTORola dtoRola)
        {
            var userManager = new UserManager <ApplicationUser>(new UserStore <ApplicationUser>(_context));

            await userManager.RemoveFromRoleAsync(dtoRola.KorisnikID, dtoRola.Rola);
        }
        private async Task DodajRolu(DTORola dtoRola)
        {
            var userManager = new UserManager <ApplicationUser>(new UserStore <ApplicationUser>(_context));

            await userManager.AddToRoleAsync(dtoRola.KorisnikID, dtoRola.Rola);
        }