Add VSIIngestFile()

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26194 f0d54148-0727-0410-94bb-9a71ac55c965
CPLParseXMLFile() and OGRGeoJSONDataSource::ReadFromFile(): use VSIIngestFile()

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@26195 f0d54148-0727-0410-94bb-9a71ac55c965