Added RasterSource/GDALBand GDAL objects

Based on Daniel Wiesmann's raster branch. Refs #23804.
I updated the file on my branch such that the wkt contains the correct information. `ds.srs.srid` returns  `3086`

https://github.com/geodesign/django/blob/raster/django/contrib/gis/gdal/tests/data/raster.tif