Optimize file path deduplication

[djaglowski]

Description of Changes

Please check that the PR fulfills these requirements

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• Add a changelog entry (for non-trivial bug fixes / features)
• CI passes

[djaglowski]

Log Files	Logs / Second	CPU Avg (%)	CPU Avg Δ (%)	Memory Avg (MB)	Memory Avg Δ (MB)
1	1000	1.4655087	-1.4485824	126.08257	-2.0510483
1	5000	4.896736	-0.4482417	134.87447	-0.25039673
1	10000	9.724287	+0.34487343	145.05873	-1.1803589
1	50000	46.673244	-7.6293945e-05	175.44046	-4.62204
1	100000	93.0854	+13.242065	232.2834	-476.29987
10	100	1.9655895	+0.0689764	134.43602	-0.76400757
10	500	5.8102927	+0.12058449	137.48276	-6.424301
10	1000	11.051659	+0.051599503	146.8971	+0.7549896
10	5000	50.640274	-0.51363754	175.16325	-7.907196
10	10000	106.00197	+10.494522	230.73627	+7.108032

[codecov]

Codecov Report

Merging #444 (309debc) into master (6cb9877) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #444      +/-   ##
==========================================
+ Coverage   72.81%   72.86%   +0.05%     
==========================================
  Files         126      126              
  Lines        8209     8209              
==========================================
+ Hits         5977     5981       +4     
+ Misses       1720     1718       -2     
+ Partials      512      510       -2     

Impacted Files	Coverage Δ
operator/builtin/input/file/finder.go	100.00% <100.00%> (+14.29%)	⬆️
operator/builtin/output/forward/forward.go	64.20% <0.00%> (+2.47%)	⬆️

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