Expert Config Page moved SfxTabPage to ModalDialog. It has its own
window as requested on this bug. Double click works as edit button
now for better usability. Also Default button renamed as Reset button.

Change-Id: Ie4732860b9677a313697d5faa72109c8b16b9c2d
Reviewed-on: https://gerrit.libreoffice.org/6704Tested-by: LibreOffice gerrit bot <gerrit@libreoffice.org>
Reviewed-by: Thorsten Behrens <thb@documentfoundation.org>
Tested-by: Thorsten Behrens <thb@documentfoundation.org>