refactor: reuse operation logs for backup/restore

[Shadow53]

Resolves #107.

Previous code iterated over files twice, which invoked more I/O than necessary.

This creates a couple functions that return an iterator that can be used without invoking disk I/O.

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[codecov]

Codecov Report

Merging #111 (acd9414) into main (1140b71) will decrease coverage by 0.11%.
The diff coverage is 87.82%.

@@            Coverage Diff             @@
##             main     #111      +/-   ##
==========================================
- Coverage   90.49%   90.37%   -0.12%     
==========================================
  Files          69       69              
  Lines        4932     5027      +95     
==========================================
+ Hits         4463     4543      +80     
- Misses        469      484      +15     

Impacted Files	Coverage Δ
src/hoard/iter/operation.rs	82.85% <50.00%> (ø)
src/checkers/history/operation/mod.rs	81.85% <65.00%> (-1.35%)	⬇️
src/command/backup_restore.rs	75.86% <90.90%> (+0.86%)	⬆️
src/hoard/mod.rs	66.66% <94.73%> (+66.66%)	⬆️
src/checkers/history/operation/v2.rs	94.75% <100.00%> (+1.08%)	⬆️
src/checkers/mod.rs	100.00% <100.00%> (ø)
src/checkers/history/last_paths.rs	93.27% <0.00%> (-5.89%)	⬇️

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