Regression from https://cgit.freedesktop.org/libreoffice/core/commit/?id=fcf9c22e00db0107391775f51fac53555711b951
Use an hashmap to find the right helpText

Change-Id: Ie3389406525fb068fb24262a40b8e6af4c744100
Reviewed-on: https://gerrit.libreoffice.org/37334Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>