Release note: none

Informs cockroachdb#51576

If filters exist on a lookup join that match columns that we are doing
the lookup against add them to the lookupExpr in the join reader spec
and build those filters into the multispan generator.

If we have inequality conditions we need to be able to lookup of the
prefix for keys found against range spans and not just point spans so
build a sorted slice of span+inputRowIndices we can binary search on.

Issue cockroachdb#51576 also encompasses allowing inequalities on columns from the
index to reference columns from the input, that will come in a later
commit.

Release note (sql change): Improve performance of lookup joins in some
cases. If join inequality conditions can be matched to index columns
include the conditions in the index lookup spans and remove them from
the runtime filters.