Add profiling and throughput reporting to the benchmarks

[alexander-beedie]

While looking for opportunities to improve performance, I extended the benchmarking script with additional profiling and throughput info/options 👍

Three main additions:

• A new kB/s stat/column

  Scaling benchmarks only catch super-linear growth; a uniform slowdown would leave every exponent exactly where it was, bit would show up here.

  $ python benchmarks/bench_parse_throughput.py --vector "UNION ALL"
  
  UNION ALL chain:
           n      input         time    ratio     kB/s  status
         100     9885 B      32.2 ms        -      307  ok
         200    20.0 kB      62.3 ms    1.94x      321  ok
         400    40.2 kB     136.2 ms    2.19x      295  ok
         800    80.7 kB     317.4 ms    2.33x      254  ok
    scaling exponent 1.17 (1.0 linear, 2.0 quadratic)  =>  linear
  
  verdict: linear  (1 vector, 0 super-linear)
  

• --profile

  Runs each vector once (at its largest size) and print the hottest frames by tottime

  $ python benchmarks/bench_parse_throughput.py --vector "UNION ALL" --profile --profile-top 6
  
  UNION ALL chain:  n=800, 80.7 kB
    ncalls  tottime  percall  cumtime  percall filename:lineno(function)
       680760    0.067    0.000    0.067    0.000 {method 'match' of 're.Pattern' objects}
       323171    0.061    0.000    0.125    0.000 sqlparse/utils.py:81(imt)
     47211/11    0.060    0.000    0.160    0.015 sqlparse/engine/grouping.py:478(_group)
        30398    0.056    0.000    0.140    0.000 sqlparse/lexer.py:106(get_tokens)
        60009    0.049    0.000    0.188    0.000 sqlparse/sql.py:235(_token_matching)
          800    0.043    0.000    0.083    0.000 sqlparse/sql.py:310(token_index)
  

• bench_parse_throughput.py

  Covers a selection of large/realistic SQL not found in the other scripts: CTEs, joins, window functions, UNION ALL chains, multi-statement scripts, comment-heavy text.

---

Found several nice speedups using the new flags, for which I'll make separate PRs shortly.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.20%. Comparing base (111b35c) to head (1cd995b).
⚠️ Report is 25 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #879      +/-   ##
==========================================
+ Coverage   97.13%   97.20%   +0.07%     
==========================================
  Files          31       31              
  Lines        3663     3793     +130     
  Branches      328      344      +16     
==========================================
+ Hits         3558     3687     +129     
- Misses         63       65       +2     
+ Partials       42       41       -1     

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