tpcbench.py add --query support to run custom query

[zhangxffff]

1. add --query argument suport for tpcbench.py to run custom query with tpch tables.
2. fix scripts in docs/contributing.md

[zhangxffff]

test in local environment

>> RAY_COLOR_PREFIX=1 RAY_DEDUP_LOGS=0 python tpcbench.py --data=tpch --concurrency=2 --batch-size=8182 --worker-pool-min=10 --validate --query 'select c.c_name, sum(o.o_totalprice) as total from orders o inner join customer c on o.o_custkey = c.c_custkey group by c_name order by c_name limit 1' 
Executing custom query:  select c.c_name, sum(o.o_totalprice) as total from orders o inner join customer c on o.o_custkey = c.c_custkey group by c_name order by c_name limit 1
2025-03-12 11:30:36,038 INFO worker.py:1832 -- Started a local Ray instance. View the dashboard at http://127.0.0.1:8265 
Registering table customer using path tpch/customer.parquet
Registering table lineitem using path tpch/lineitem.parquet
Registering table nation using path tpch/nation.parquet
Registering table orders using path tpch/orders.parquet
Registering table part using path tpch/part.parquet
Registering table partsupp using path tpch/partsupp.parquet
Registering table region using path tpch/region.parquet
Registering table supplier using path tpch/supplier.parquet
Writing results to datafusion-ray-tpch-1741750238210.json
statements = ['select c.c_name, sum(o.o_totalprice) as total from orders o inner join customer c on o.o_custkey = c.c_custkey group by c_name order by c_name limit 1']
executing  select c.c_name, sum(o.o_totalprice) as total from orders o inner join customer c on o.o_custkey = c.c_custkey group by c_name order by c_name limit 1
+--------------------+-----------+
| c_name             | total     |
+--------------------+-----------+
| Customer#000000001 | 587762.91 |
+--------------------+-----------+
done with query custom query
{
    "engine": "datafusion-ray",
    "benchmark": "tpch",
    "settings": {
        "concurrency": 2,
        "batch_size": 8182,
        "prefetch_buffer_size": 0,
        "partitions_per_worker": null
    },
    "data_path": "tpch",
    "queries": {
        "custom query": 0.19914793968200684
    },
    "validated": {
        "custom query": true
    }
}
benchmark complete. sleeping for 3 seconds for ray to clean up

[zhangxffff]

Hi @robtandy , Would you mind reviewing this PR when you get a chance? This is the follow-up work we had discussed in #82 . Thanks for your time!