ENH: add GeoJSON driver and simplify driver selection

OTB is not able to create vector files in GeoJSON format although gdal provides the feature. This is due to the fact that gdal vector drivers have to be explicitly enabled in OTB. This MR adds the GeoJSON driver. It also takes the opportunity to clean up a little bit the logic for the driver selection.

Modules/IO/IOGDAL/include/otbOGRVectorDataIO.h

@@ -22,6 +22,7 @@
 #define otbOGRVectorDataIO_h
 
 #include <string>
+#include <map>
 #include <cassert>
 
 #include "otbVectorDataIOBase.h"
@@ -124,6 +125,19 @@ private:
 
   GDALDataset * m_DataSource;
 
+  const std::map<std::string, std::string> 
+    m_OGRExtensionsToDrivers = {
+                                { ".SHP", "ESRI Shapefile"},
+                                { ".TAB", "MapInfo File"},
+                                { ".GML", "GML"},
+                                { ".GPX", "GPX"},
+                                { ".SQLITE", "SQLite"},
+                                {".KML", "KML"},
+                                { ".GMT", "OGR_GMT"},
+                                { ".GPKG", "GPKG"},
+                                { ".JSON", "GeoJSON"},
+                                { ".GEOJSON", "GeoJSON"}
+  };
 };
 
 } // end namespace otb