unmarshall varchar, text, blob, ascii cql types with zero data into ([]byte)(nil), (*[]byte)(*[nil])

[illia-li]

According to cql protocol - for all cql types value can be nil and zero.
Therefore all unmarshall functions for cql types should unmarshalls nil data into nil go value and zero data into zero go value.
But currently, for varchar, text, blob, ascii cql types zero data unmarshalls into ([]byte)(nil), (*[]byte)(*[nil])

[illia-li]

This issue is also present in uuid, timeuuid cql types