Respect Qt::ImhNoTextHandles

Change-Id: I0f2481b2650a0a43623e8ece21d89e668c348a86
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>
Reviewed-by: Jarkko Koivikko <jarkko.koivikko@code-q.fi>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>