perf: optimize reading transactions in commit loop

[wjones127]

• Cache transaction files
• Read transaction files with concurrency within commit loop

Closes #3057

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 70.70707% with 29 lines in your changes missing coverage. Please review.

Project coverage is 77.10%. Comparing base (4ab270b) to head (9b88d10).

Files with missing lines	Patch %	Lines
rust/lance/src/io/commit.rs	80.45%	5 Missing and 12 partials ⚠️
rust/lance-table/src/format/fragment.rs	0.00%	2 Missing and 4 partials ⚠️
rust/lance/src/dataset/transaction.rs	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3117      +/-   ##
==========================================
- Coverage   77.12%   77.10%   -0.02%     
==========================================
  Files         240      240              
  Lines       80652    80698      +46     
  Branches    80652    80698      +46     
==========================================
+ Hits        62203    62225      +22     
- Misses      15279    15297      +18     
- Partials     3170     3176       +6     

Flag	Coverage Δ
unittests	77.10% <70.70%> (-0.02%)	⬇️

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