GTiff: support unsetting geotiff tags when calling SetGeoTransform([0,1,0,0,0,1]) and SetProjection('')

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@25548 f0d54148-0727-0410-94bb-9a71ac55c965
gdal_edit.py: promote it as an 'official' tool (#4963)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@25549 f0d54148-0727-0410-94bb-9a71ac55c965
Update NEWS [ci skip]

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@25550 f0d54148-0727-0410-94bb-9a71ac55c965