RFR: 8315968: Consolidate java.util.Digits and StringLatin1::PACKED_DIGITS [v14]

[温绍锦]

> Some codes in core libs are duplicated, including:
> java.util.DecimalDigits::DIGITS -> java.lang.StringLatin1.PACKED_DIGITS
> java.util.DecimalDigits::size -> java.lang.Long.stringSize
> 
> We can reduce duplication through JavaLangAccess, which is also needed in other places, such as:
> https://github.com/openjdk/jdk/pull/15555

温绍锦 has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:

  rebase & resolve DecimalDigits delete and add

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Changes: https://git.openjdk.org/jdk/pull/15651/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15651&range=13
  Stats: 577 lines in 13 files changed: 274 ins; 279 del; 24 mod
  Patch: https://git.openjdk.org/jdk/pull/15651.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15651/head:pull/15651

PR: https://git.openjdk.org/jdk/pull/15651