Implement comparison functions for SELECT clause

The following functions aren't supported in the SELECT clause in columnstore
Item::COND_ITEM
Item_func::EQ_FUNC
Item_func::NE_FUNC
Item_func::LT_FUNC
Item_func::LE_FUNC
Item_func::GE_FUNC
Item_func::GT_FUNC
Item_func::LIKE_FUNC
Item_func::BETWEEN
Item_func::IN_FUNC
Item_func::ISNULL_FUNC
Item_func::ISNOTNULL_FUNC
Item_func::NOT_FUNC
Item_func::EQUAL_FUNC

These appear in situations like
SELECT a=1 from t1;
Which would generate a EQ_FUNC.