<i18n dev> RFR: 8358880: Performance of parsing with DecimalFormat can be improved

[Johannes Graham]

This PR replaces construction of intermediate strings to be parsed with more direct manipulation of numbers. It also has a more streamlined mechanism of handling `Long.MIN_VALUE` when parsing longs by using `Long.parseUnsignedLong`

As a small side-effect it also eliminates the use of a cached StringBuilder in DigitList.

Testing:
- GHA
- Local run of tier 2 and jtreg:jdk/java/text
- New benchmark: DecimalFormatParseBench

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

Commit messages:
 - Merge branch 'openjdk:master' into digitlist-getdouble-get-long
 - simplify getBigDecimal
 - simplify comparison
 - update comment
 - copyright dates
 - improve getDouble, getLong

Changes: https://git.openjdk.org/jdk/pull/25644/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25644&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8358880
  Stats: 177 lines in 4 files changed: 119 ins; 46 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/25644.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25644/head:pull/25644

PR: https://git.openjdk.org/jdk/pull/25644