feat(executor_v2): migrate executors to run TPCH

[wangrunji0408]

This PR migrates the following executors to fit the new planner:

• CreateTable / Drop
• Insert
• CopyFrom / CopyTo
• NestedLoopJoin / HashJoin
• SimpleAgg / HashAgg
• Limit
• Order / TopN

TPCH Q1,3,5,6,10 is able to run. But Q6 will produce a wrong result due to an incorrect decimal cast.

This PR also adds support for showing column names in explain. Here is an example of TPCH Q3:

Projection: [l_orderkey, sum((l_extendedprice * (1 - l_discount))), o_orderdate, o_shippriority] (cost=57537.88)              
  TopN: limit=10, offset=0, orderby=[sum((l_extendedprice * (1 - l_discount))) desc, o_orderdate asc] (cost=57487.88)         
    Aggregate: [sum((l_extendedprice * (1 - l_discount)))], groupby=[l_orderkey, o_orderdate, o_shippriority] (cost=56064.105)
      HashJoin: inner, on=([o_orderkey] = [l_orderkey]) (cost=53584.105)                                                      
        HashJoin: inner, on=([c_custkey] = [o_custkey]) (cost=22651.05)                                                       
          Filter: (c_mktsegment = 'BUILDING') (cost=2700)                                                                     
            Scan: [c_custkey, c_mktsegment] (cost=2000)                                                                       
          Filter: (1995-03-15 > o_orderdate) (cost=7500)                                                                      
            Scan: [o_orderkey, o_custkey, o_orderdate, o_shippriority] (cost=4000)                                            
        Filter: (l_shipdate > 1995-03-15) (cost=7500)                                                                         
          Scan: [l_orderkey, l_extendedprice, l_discount, l_shipdate] (cost=4000)                                             

[skyzh]

Good work!

[skyzh]

Indeed now I'm inclined not to have DropTableExecutor / CreateTableExecutor like what DuckDB did... create / drop table are pure catalog operations and can be handled after binding.