Rasql_Update should add NULL VALUES parameter from source collection

[Bang Pham Huu]

When a collection is created with null values, e.g:

CREATE TYPE gistw_landsat7_Set AS SET (gistw_landsat7_Array NULL VALUES [0])

and importing file does not contain this null values: 0, then rasql should automatically add this null value in UPDATE command, e.g:

UPDATE gistw_landsat7 SET gistw_landsat7[0:8140,0:7090] ASSIGN decode(<[0:0] 1c>, "GDAL", 
"{\"filePaths\":[\"/home/rasdaman/tmp/Landsat7_taiwan/1_LE07_L1TP_117043_20181116_20181116_01_RT_B1.TIF\"]}") NULL VALUES [0] 
WHERE oid(gistw_landsat7) = 519169