⚡️ Tidy and optimize LibString

[Vectorized]

Description

♻️

Checklist

Ensure you completed all of the steps below before submitting your pull request:

• Ran forge fmt?
• Ran forge test?

Pull requests with an incomplete checklist will be thrown out.

[github-actions]

Gas Snapshot Comparison Report

Generated at commit : ce832b8, Compared to commit : 79f2c77

Contract Name	Test Name	Main Gas	PR Gas	Diff
Base64Test	test__codesize()	6841	6816	-25
ERC1271Test	testIsValidSignature()	2390984	2390883	-101
	test__codesize()	29885	29878	-7
JSONParserLibTest	testDecodeInvalidStringReverts()	172924	172813	-111
	testDecodeString()	193269	193119	-150
	testParseInt()	204229	204099	-130
	testParseInvalidIntReverts()	210681	210550	-131
	testParseInvalidNumberReverts()	4068682	4067432	-1250
	testParseInvalidReverts()	8589165	8587164	-2001
	testParseInvalidStringReverts()	2117157	2116357	-800
	testParseInvalidUintReverts()	308887	308736	-151
	testParseJWTGas()	50023	50006	-17
	testParseRecursiveObject()	94907	94896	-11
	testParseSpecials()	260199	260188	-11
	testParseString()	1237483	1237179	-304
	testParseUint()	95659	95589	-70
	testParseUintFromHex()	1382724	1385870	3146
	test__codesize()	38087	38063	-24
LibCloneTest	testCloneDeterministicWithImmutableArgs()	128890	128886	-4
	testCloneWithImmutableArgs()	129436	129432	-4
	testDeployERC1967BeaconProxyWithImmutableArgs()	879000	878998	-2
LibStringTest	testContains()	44000	43926	-74
	testStringEscapeHTML()	8427	7973	-454
	testStringEscapeJSON()	39797	39401	-396
	testStringEscapeJSONHexEncode()	712815	709115	-3700
	testStringIndexOf()	17375	17329	-46
	testStringIndicesOf()	11700	11542	-158
	testStringLowerDifferential()	3725445	3411555	-313890
	testStringPackAndUnpackOne()	4029923	737456	-3292467
	testStringPackAndUnpackTwo()	896840	895109	-1731
	testStringRepeat()	4986	4936	-50
	testStringReplaceLong()	8573	8136	-437
	testStringReplaceMedium()	7581	7319	-262
	testStringReplaceShort()	12329	11654	-675
	testStringSlice()	9257	9239	-18
	testStringSplit()	20309	20211	-98
	testStringUpperDifferential()	3084191	3110704	26513
	testToStringPositiveNumberBrutalized()	588450	586828	-1622
	testToStringUint256MaxBrutalized()	600016	598361	-1655
	testToStringZeroBrutalized()	587988	586333	-1655
	test__codesize()	46388	46318	-70
MetadataReaderLibTest	testReadBytes32StringTruncated()	775178	775102	-76
	testReadStringChopped()	272350	272322	-28