sql: Assert correct types on virtual schema row population
sql: Assert correct types on virtual schema row population

Closes #9577.

This change asserts the type of all datums passed to the virtual schema
row population function, making sure the datum type matches its
corresponding column type.

petermattis/cockroach,vaibhavarora/cockroach,veteranlu/cockroach,paperstreet/cockroach,paperstreet/cockroach,glycerine/cockroach,maxlang/cockroach,paperstreet/cockroach,cockroachdb/cockroach,maxlang/cockroach,paperstreet/cockroach,petermattis/cockroach,cockroachdb/cockroach,veteranlu/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,vaibhavarora/cockroach,maxlang/cockroach,veteranlu/cockroach,petermattis/cockroach,petermattis/cockroach,glycerine/cockroach,vaibhavarora/cockroach,glycerine/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,petermattis/cockroach,cockroachdb/cockroach,veteranlu/cockroach,glycerine/cockroach,petermattis/cockroach,cockroachdb/cockroach,maxlang/cockroach,maxlang/cockroach,cockroachdb/cockroach,glycerine/cockroach,cockroachdb/cockroach,maxlang/cockroach,paperstreet/cockroach,petermattis/cockroach,glycerine/cockroach,maxlang/cockroach,vaibhavarora/cockroach,glycerine/cockroach,petermattis/cockroach,cockroachdb/cockroach,vaibhavarora/cockroach,veteranlu/cockroach,veteranlu/cockroach,vaibhavarora/cockroach,veteranlu/cockroach,maxlang/cockroach,glycerine/cockroach,paperstreet/cockroach,paperstreet/cockroach,paperstreet/cockroach