[jdk21u-dev] RFR: 8311220: Optimization for StringLatin UpperLower

[Roman Marchenko]

This is backport of "[JDK-8311220](https://bugs.openjdk.org/browse/JDK-8311220) Optimization for StringLatin UpperLower"

It seems good to have it backported as I see improvements even locally on my i7-12700H (benchmarks command line was taken from original PR):

sh make/devkit/createJMHBundle.sh
bash configure --with-jmh=build/jmh/jars
make test TEST="micro:java.lang.StringUpperLower.*"

----- Baseline JDK21
Benchmark                      Mode  Cnt   Score   Error  Units
StringUpperLower.lowerToLower  avgt   15  24.146 ± 0.216  ns/op
StringUpperLower.lowerToUpper  avgt   15  43.720 ± 2.689  ns/op
StringUpperLower.mixedToLower  avgt   15  27.335 ± 1.120  ns/op
StringUpperLower.mixedToUpper  avgt   15  43.239 ± 3.731  ns/op
StringUpperLower.upperToLower  avgt   15  28.310 ± 1.557  ns/op
StringUpperLower.upperToUpper  avgt   15  35.032 ± 1.840  ns/op

----- Backported
Benchmark                      Mode  Cnt   Score   Error  Units
StringUpperLower.lowerToLower  avgt   15  13.890 ± 0.786  ns/op
StringUpperLower.lowerToUpper  avgt   15  38.636 ± 2.103  ns/op
StringUpperLower.mixedToLower  avgt   15  28.087 ± 1.639  ns/op
StringUpperLower.mixedToUpper  avgt   15  33.970 ± 0.502  ns/op
StringUpperLower.upperToLower  avgt   15  28.394 ± 1.443  ns/op
StringUpperLower.upperToUpper  avgt   15  17.347 ± 0.578  ns/op

-------------

Commit messages:
 - Backport f09b7af6851c725b0fc4d63832b52e17c4d24836

Changes: https://git.openjdk.org/jdk21u-dev/pull/1988/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1988&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311220
  Stats: 14 lines in 1 file changed: 1 ins; 7 del; 6 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1988.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1988/head:pull/1988

PR: https://git.openjdk.org/jdk21u-dev/pull/1988