Return the result of "password migration" procedure
    
    So far "migration" end point redirected to "error"/"invalid" page as
    a result of the client request. To use ajax requests and to not
    reload/load the whole page the response should include the result of
    request.
    
    Fixes: https://pagure.io/freeipa/issue/7641
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Petr Vobornik <pvoborni@redhat.com>
    Reviewed-By: Serhii Tsymbaliuk <stsymbal@redhat.com>