DolphinSettingsDialog: Move focus to Okay button last

DolphinSettingsDialog: Move focus to Okay button last

This commit changes the Tab order in Dolphin's Configure dialog
so that the items which are visually at the end of the dialog are
also last in the keyboard focus order when cycling through the
interface using the Tab key.

Previously, the "Cancel", "Defaults", "Okay", and "Apply" buttons
received focus prior to the actual contents of the pages which
does not make sense from a workflow perspective.

This change should also make navigating this dialog easier when
relying on screen readers because reading those buttons out prior
to users even having a chance to change any setting did not make
any sense.