refactor: use b.Loop() to simplify the code and improve performance

[dulanting]

Description:

These changes use b.Loop() to simplify the code and improve performance
Supported by Go Team, more info: https://go.dev/blog/testing-b-loop  and https://go.dev/issue/73137

Before:

 go test -run=^$ -bench=. ./pkg/decoders                  
goos: darwin
goarch: arm64
pkg: github.com/trufflesecurity/trufflehog/v3/pkg/decoders
cpu: Apple M4
BenchmarkFromChunkSmall-10                	 6595539	       181.3 ns/op
BenchmarkFromChunkMedium-10               	  466124	      2224 ns/op
BenchmarkFromChunkLarge-10                	33437010	        34.91 ns/op
BenchmarkDecodeOriginalEscape-10          	50474690	        42.09 ns/op
BenchmarkDecodeCodePoint-10               	  880795	      1218 ns/op
BenchmarkDecodeBraceEscape-10             	48463552	        49.64 ns/op
BenchmarkDecodeLongEscape-10              	43757558	        56.57 ns/op
BenchmarkDecodePerlEscape-10              	46256365	        68.06 ns/op
BenchmarkDecodeCssEscape-10               	50212356	        23.12 ns/op
BenchmarkDecodeHtmlEscape-10              	47056438	        59.62 ns/op
BenchmarkDecodePercentEscape-10           	50229433	        40.58 ns/op
BenchmarkFromChunk_OriginalFormat-10      	  998955	      1168 ns/op
BenchmarkFromChunk_BraceFormat-10         	 1000000	      1168 ns/op
BenchmarkFromChunk_LongFormat-10          	  603687	      2029 ns/op
BenchmarkFromChunk_HtmlFormat-10          	  999502	      1237 ns/op
BenchmarkFromChunk_MixedContent-10        	  198066	      5813 ns/op
BenchmarkFromChunk_NoUnicode-10           	  258198	      4645 ns/op
BenchmarkFromChunk_LargeData-10           	     528	   2244064 ns/op
BenchmarkRegexMatching_AllPatterns-10     	  124023	      9874 ns/op
BenchmarkRegexMatching_NoMatch-10         	  245246	      4659 ns/op
BenchmarkFromChunk_MemoryAllocation-10    	  197952	      6189 ns/op	   14398 B/op	      86 allocs/op
BenchmarkUtf16ToUtf8-10                   	28343331	        38.98 ns/op
Benchmark_extractSubstrings-10            	 5197101	       222.4 ns/op
PASS
ok  	github.com/trufflesecurity/trufflehog/v3/pkg/decoders	41.076s

After:

go test -run=^$ -bench=. ./pkg/decoders                   
goos: darwin
goarch: arm64
pkg: github.com/trufflesecurity/trufflehog/v3/pkg/decoders
cpu: Apple M4
BenchmarkFromChunkSmall-10                	 6542812	       172.2 ns/op
BenchmarkFromChunkMedium-10               	  642433	      1850 ns/op
BenchmarkFromChunkLarge-10                	39467463	        30.15 ns/op
BenchmarkDecodeOriginalEscape-10          	51547774	        23.02 ns/op
BenchmarkDecodeCodePoint-10               	  918812	      1209 ns/op
BenchmarkDecodeBraceEscape-10             	44588186	        25.17 ns/op
BenchmarkDecodeLongEscape-10              	45711601	        26.57 ns/op
BenchmarkDecodePerlEscape-10              	43454577	        26.05 ns/op
BenchmarkDecodeCssEscape-10               	50294870	        23.55 ns/op
BenchmarkDecodeHtmlEscape-10              	43514719	        24.98 ns/op
BenchmarkDecodePercentEscape-10           	49723412	        24.82 ns/op
BenchmarkFromChunk_OriginalFormat-10      	  960178	      1216 ns/op
BenchmarkFromChunk_BraceFormat-10         	 1000000	      1168 ns/op
BenchmarkFromChunk_LongFormat-10          	  625647	      1924 ns/op
BenchmarkFromChunk_HtmlFormat-10          	  992942	      1167 ns/op
BenchmarkFromChunk_MixedContent-10        	  202584	      5804 ns/op
BenchmarkFromChunk_NoUnicode-10           	  253852	      4512 ns/op
BenchmarkFromChunk_LargeData-10           	     536	   2221862 ns/op
BenchmarkRegexMatching_AllPatterns-10     	  125577	      9504 ns/op
BenchmarkRegexMatching_NoMatch-10         	  261069	      4548 ns/op
BenchmarkFromChunk_MemoryAllocation-10    	  195384	      5780 ns/op	   14393 B/op	      86 allocs/op
BenchmarkUtf16ToUtf8-10                   	31611598	        37.37 ns/op
Benchmark_extractSubstrings-10            	 5364784	       224.2 ns/op
PASS
ok  	github.com/trufflesecurity/trufflehog/v3/pkg/decoders	27.924s

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?

[CLAassistant]

All committers have signed the CLA.

[rosecodym]

Thank you for this change, and particularly for the links to commentary explaining it! It's nice to have that stuff in the commit history.