Improve index advisor to handle `self` queries

SELECT ENCODED_SIZE(d)

FROM `EverC` AS d

WHERE ENCODED_SIZE(d) > 230 

and ENCODED_SIZE(d) < 247;

Above query recommends covered secondary index.

SELECT ENCODED_SIZE(self)

FROM `EverC` 

WHERE ENCODED_SIZE(self) > 230 

and ENCODED_SIZE(self) < 247;

But the same query with "self" only recommends the primary index.  I understand that the indexer may not be able to use the planner for `self` but in the advisor perhaps we could have a special message that says "if using `self`, please replace with a proper alias to advise on the query.  A query that uses `self` will function in the same way"