RFR: 8315585: Optimization for decimal to string [v6]

[Shaojin Wen]

> Continue to complete PR #16006 and PR #21593 to improve BigDecimal::toString and BigDecimal::toPlainString performance and reduce duplicate code

Shaojin Wen has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 37 commits:

 - Merge remote-tracking branch 'upstream/master' into dec_to_str_202501
 - simplify layoutChars
 - comments, from @liach
 - getValueString -> getCompactValueString, from @liach
 - Refactor BigDecimal string creation to use JLA.uncheckedNewStringWithLatin1Bytes
   
   Co-authored-by: Qwen-Coder <qwen-coder at alibabacloud.com>
 - Merge remote-tracking branch 'upstream/master' into dec_to_str_202501
   
   # Conflicts:
   #	src/java.base/share/classes/java/math/BigDecimal.java
 - Merge remote-tracking branch 'upstream/master' into dec_to_str_202501
   
   # Conflicts:
   #	src/java.base/share/classes/java/math/BigDecimal.java
   #	src/java.base/share/classes/jdk/internal/util/DecimalDigits.java
   #	test/micro/org/openjdk/bench/java/math/BigDecimals.java
 - Merge remote-tracking branch 'upstream/master' into dec_to_str_202501
 - Merge remote-tracking branch 'upstream/master' into dec_to_str_202501
   
   # Conflicts:
   #	src/java.base/share/classes/jdk/internal/util/DecimalDigits.java
 - remove getChars(long, int, char[])
 - ... and 27 more: https://git.openjdk.org/jdk/compare/3f33eaa4...32d95b36

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Changes: https://git.openjdk.org/jdk/pull/23310/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23310&range=05
  Stats: 449 lines in 3 files changed: 243 ins; 108 del; 98 mod
  Patch: https://git.openjdk.org/jdk/pull/23310.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23310/head:pull/23310

PR: https://git.openjdk.org/jdk/pull/23310