`expr_constant(, typed_logical_null = )`

[romainfrancois]

This is related to https://github.com/hannes/duckdb-rfuns/pull/91#discussion_r1593002667

This allows expr_constant() to construct a NULL constant of type LOGICAL which wasn't possible before.

Perhaps a better alternative would be to allow expr_constant(NULL) to construct a SQLNULL and let expr_constant(NA) to construct a Value(LogicalType::BOOLEAN) ?

expr_constant(NULL) is currently an error