GPKG: add raster creation capability

git-svn-id: https://svn.osgeo.org/gdal/trunk@28060 f0d54148-0727-0410-94bb-9a71ac55c965
Fix in gpkg.py for Windows

git-svn-id: https://svn.osgeo.org/gdal/trunk@28061 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' into trunk_vc12