NewGRF: Add/extend station variables for station info of nearby tiles

In preparation for support of more than 255 stations per GRF

src/table/newgrf_debug_data.h

@@ -584,6 +584,8 @@ static const NIVariable _niv_stations[] = {
 	NIV(0x68, "station info of nearby tiles"),
 	NIV(0x69, "information about cargo accepted in the past"),
 	NIV(0x6A, "GRFID of nearby station tiles"),
+	NIV(A2VRI_STATION_INFO_NEARBY_TILES_EXT, "station info of nearby tiles ext"),
+	NIV(A2VRI_STATION_INFO_NEARBY_TILES_V2, "station info of nearby tiles v2"),
 	NIV_END()
 };