ref: Various cleanup tasks

[loewenheim]

• Use chars instead of char_indices in one instance
• Remove ClassIndex functionality (superseded by ProguardCache)
• Use dep: syntax for uuid dependency
• Update edition to 2021
• Commit Cargo.lock

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 77.72%. Comparing base (214ec5a) to head (5cfabb2).
Report is 27 commits behind head on master.

Files	Patch %	Lines
src/java.rs	50.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #43      +/-   ##
==========================================
- Coverage   85.89%   77.72%   -8.18%     
==========================================
  Files           4        7       +3     
  Lines        1617     2272     +655     
==========================================
+ Hits         1389     1766     +377     
- Misses        228      506     +278     

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