Optimization for StringLatin UpperLower

Create on behalf of shaojin.wensj@alibaba-inc.com
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Benchmark Mode Cnt Score Error Units (baseliine)
-StringUpperLower.lowerToLower avgt 15 25.350 ± 0.071 ns/op
-StringUpperLower.lowerToUpper avgt 15 53.722 ± 0.127 ns/op
-StringUpperLower.mixedToLower avgt 15 40.172 ± 0.103 ns/op
-StringUpperLower.mixedToUpper avgt 15 46.546 ± 0.132 ns/op
-StringUpperLower.upperToLower avgt 15 39.505 ± 0.213 ns/op
-StringUpperLower.upperToUpper avgt 15 26.066 ± 0.050 ns/op

+Benchmark Mode Cnt Score Error Units (PR)
+StringUpperLower.lowerToLower avgt 15 19.218 ± 0.047 ns/op (+31.90%)
+StringUpperLower.lowerToUpper avgt 15 50.169 ± 0.181 ns/op (+7.08%)
+StringUpperLower.mixedToLower avgt 15 38.324 ± 0.128 ns/op (+4.82%)
+StringUpperLower.mixedToUpper avgt 15 44.640 ± 0.340 ns/op (+4.26%)
+StringUpperLower.upperToLower avgt 15 37.709 ± 0.202 ns/op (+18.38%)
+StringUpperLower.upperToUpper avgt 15 11.305 ± 0.016 ns/op (+130.57%)