QHeaderView - renaming functions in Qt5

QHeaderView - renaming functions in Qt5

This patch renames the functions in Qt5 according to the
notes. It also renames resizeMode to be consistent.

The old functions are both marked with both QT_DEPRECATED
and '### Qt 6 - remove'

All usage of the function within the qtbase are also
changed to use the new functions.

Change-Id: I9e05fa41d232e9ca43b945fcc949987017f3aedd
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>