[widgets][parameterwidget] Improve widget size handling

The widget had much empty space because the QStackedWidget
used to contain the editors calculates the size based on
the biggest widget within it. This patch changes that
so that we can adjust the size of the QStackedWidget to
be more compact whathever the current widget shown.
2 jobs for 240_improve_parameter_widget_size in 25 minutes and 17 seconds (queued for 4 seconds)