generateRandom() does not support generating random Date32 value:

```
SELECT *
FROM generateRandom('Date32 Date32', NULL, 10, 2)
LIMIT 10

Received exception from server (version 21.11.5):
Code: 48. DB::Exception: Received from localhost:9000. DB::Exception: The 'GenerateRandom' is not implemented for type Date32: While executing GenerateRandom. (NOT_IMPLEMENTED)
```

pcg64 & rng,
    ContextPtr context)
{
    TypeIndex idx = type->getTypeId();
    switch (idx)
    {
        case TypeIndex::String:
        {
            
            auto column = ColumnString::create();
            ColumnString::Chars & data_to = column->getChars();
            ColumnString::Offsets & offsets_to = column->getOffsets();
            offsets_to.resize(limit);
            IColumn::Offset offset = 0;
            for (size_t row_num = 0; row_num < limit; ++row_num)
            {
                size_t length = rng() % (max_string_length + 1);    
                IColumn::Offset next_offset = offset + length + 1;
                data_to.resize(next_offset);
                offsets_to[row_num] = next_offset;
                auto * data_to_ptr = data_to.data();    
                for (size_t pos = offset, end = offset + length; pos < end; pos += 4)    
                {
                    UInt64 rand = rng();
                    UInt16 rand1 = rand;
                    UInt16 rand2 = rand >> 16;
                    UInt16 rand3 = rand >> 32;
                    UInt16 rand4 = rand >> 48;