feat: add javareach as an enrichment plugin

[hogo6002]

This is an initial PR to add javareach as an enrichment plugin. The follow-up PR will resolve things listed in #1886, after which this feature will be merged into osv-scalibr.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 53.22581% with 493 lines in your changes missing coverage. Please review.

Project coverage is 64.84%. Comparing base (44ed835) to head (a340f84).

Files with missing lines	Patch %	Lines
internal/scalibrenricher/javareach/javaclass.go	47.76%	112 Missing and 40 partials ⚠️
internal/scalibrenricher/javareach/jar.go	50.00%	99 Missing and 14 partials ⚠️
internal/scalibrenricher/javareach/javareach.go	54.91%	80 Missing and 30 partials ⚠️
internal/scalibrenricher/javareach/reachable.go	56.35%	83 Missing and 20 partials ⚠️
internal/scalibrenricher/javareach/utils.go	64.70%	10 Missing and 2 partials ⚠️
internal/scalibrenricher/javareach/uniqueq.go	86.95%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1908      +/-   ##
==========================================
- Coverage   65.60%   64.84%   -0.77%     
==========================================
  Files         167      173       +6     
  Lines       16060    17114    +1054     
==========================================
+ Hits        10536    11097     +561     
- Misses       4859     5245     +386     
- Partials      665      772     +107     

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