RFR: 8316150: Refactor get chars and string size [v22]

[温绍锦]

> 1. Reduce duplicate stringSize code
> 2. Move java.lang.StringLatin1.getChars to jdk.internal.util.DecimalDigits::getCharLatin1，not only java.lang, other packages also need to use this method

温绍锦 has updated the pull request incrementally with one additional commit since the last revision:

  Revert FormatItem related changes

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Changes:
  - all: https://git.openjdk.org/jdk/pull/15699/files
  - new: https://git.openjdk.org/jdk/pull/15699/files/8ec66cca..d4f55ddc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15699&range=21
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15699&range=20-21

  Stats: 597 lines in 9 files changed: 239 ins; 260 del; 98 mod
  Patch: https://git.openjdk.org/jdk/pull/15699.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15699/head:pull/15699

PR: https://git.openjdk.org/jdk/pull/15699