fix: compute children correlation in compute_cost (#176)

The input logical property of a group is not fixed. For example, with
semantic correlation, a join b join c, has a = b = c as output
correlation, but the input might be a = b, a = c, or b = c depending on
which join is performed first. Right now, we just take the first expr in
the group as the input, which is why we are getting the bug that the
equal columns from semantic correlation are the same as the join
condition.

We should reconstruct the input eq columns during `compute_cost` using
children's group id, not during building logical property.

optd-datafusion-repr/src/cost/base_cost/agg.rs

@@ -64,7 +64,7 @@ impl<
                 let group_col_refs = optimizer
                     .get_property_by_group::<ColumnRefPropertyBuilder>(context.group_id, 1);
                 group_col_refs
-                    .column_refs()
+                    .base_table_column_refs()
                     .iter()
                     .take(group_by.len())
                     .map(|col_ref| match col_ref {