Update Pyserini bindings to Lucene 9

[lintool]

Exposes Lucene 8 backwards compatibility bindings in SimpleSearcher and SimpleImpactSearcher.

Basically, if we detect Lucene 8 indexes, we disable consistent tie-breaking, which depends on docvalues; see #1952

Additional changes:

• general cleanup (fixed code formatting in SimpleImpactSearcher)
• killed main in SimpleSearcher
• Changed to Python method names (snake_case)

[MXueguang]

we change the name style to python style in SimpleSearchers?

[lintool]

we change the name style to python style in SimpleSearchers?

Yes... since this is a major breaking upgrade, I thought I'd do some cleanup while I was at it. This would bring closer alignment to the pyserini end.

Thoughts? Let me know if you don't think this is a good idea?

[MXueguang]

I think its good, simple(impact)searchers are for python anyway

[codecov-commenter]

Codecov Report

Merging #1961 (4c98759) into master (0fc578a) will increase coverage by 0.07%.
The diff coverage is 76.37%.

❗ Current head 4c98759 differs from pull request most recent head 6a867f3. Consider uploading reports for the commit 6a867f3 to get more accurate results

@@             Coverage Diff              @@
##             master    #1961      +/-   ##
============================================
+ Coverage     60.14%   60.21%   +0.07%     
- Complexity     1061     1065       +4     
============================================
  Files           178      178              
  Lines          9903     9811      -92     
  Branches       1371     1359      -12     
============================================
- Hits           5956     5908      -48     
+ Misses         3441     3429      -12     
+ Partials        506      474      -32     

Impacted Files	Coverage Δ
...rc/main/java/io/anserini/search/SearchMsmarco.java	0.00% <0.00%> (ø)
...n/java/io/anserini/search/SimpleTweetSearcher.java	0.00% <0.00%> (ø)
.../java/io/anserini/search/SimpleImpactSearcher.java	77.08% <76.34%> (+5.08%)	⬆️
...c/main/java/io/anserini/search/SimpleSearcher.java	65.65% <92.85%> (+2.13%)	⬆️
...anserini/rerank/lib/ScoreTiesAdjusterReranker.java	83.33% <0.00%> (+8.33%)	⬆️

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