RFR: 8343829: Unify decimal and hexadecimal parsing in FloatingDecimal [v6]

[Raffaello Giulietti]

> See the JBS bug for some details.

Raffaello Giulietti has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains nine additional commits since the last revision:

 - Remove unused BIG_DECIMAL_EXPONENT
 - Merge branch 'master' into 8343829
 - Merge branch 'master' into 8343829
 - Redacted comments.
 - Merge branch 'master' into 8343829
 - Minors in comments.
 - Removed repeated comment.
 - Refactoring some code and comments.
 - 8343829: Unify decimal and hexadecimal parsing in FloatingDecimal

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22737/files
  - new: https://git.openjdk.org/jdk/pull/22737/files/092755b4..49ed9aac

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22737&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22737&range=04-05

  Stats: 672210 lines in 9937 files changed: 267712 ins; 352817 del; 51681 mod
  Patch: https://git.openjdk.org/jdk/pull/22737.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22737/head:pull/22737

PR: https://git.openjdk.org/jdk/pull/22737