RFR: 8356709: Avoid redundant String formatting in BigDecimal.valueOf(double)

[Johannes Graham]

Optimize `BigDecimal.valueOf(double)` by using `FormattedFPDecimal` instead of converting to decimal string and then parsing it. This results in an approximate 6x improvement for me.

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Commit messages:
 - add bug number to test, fix typo
 - wait for real bug number to set it in header
 - Dates again
 - Fix licence format
 - Fix licence dates
 - Add licence, update test directives
 - Improve variable names
 - optimize BigDecimal.valueOf(double)

Changes: https://git.openjdk.org/jdk/pull/25173/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25173&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8356709
  Stats: 188 lines in 4 files changed: 179 ins; 1 del; 8 mod
  Patch: https://git.openjdk.org/jdk/pull/25173.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25173/head:pull/25173

PR: https://git.openjdk.org/jdk/pull/25173