sql: put the output of EXPLAIN (VEC) in the EXPLAIN ANALYZE (DEBUG) bundle

[RaduBerinde]

EXPLAIN ANALYZE (DEBUG) generates a bundle which contains the output of most flavors of EXPLAIN, except EXPLAIN (VEC). I tried to add it but it looks very hard to integrate with. For example, the code messes with the subqueries in planner.curPlan:

cockroach/pkg/sql/explain_plan.go

Line 216 in a1296f9

outerSubqueries := params.p.curPlan.subqueryPlans

cockroach/pkg/sql/explain_vec.go

Line 59 in a1296f9

outerSubqueries := params.p.curPlan.subqueryPlans

I believe this code could use some cleanup. Also note that EXPLAIN (VEC) doesn't work when there are subqueries. But in the case of EXPLAIN ANALYZE (DEBUG) we actually run everything. So wecould conceivably generate it, perhaps separately for each subquery/postquery. This is what we do with the distsql diagrams: the bundle contains a separate diagram for each subquery/main query/postquery.