RFR: 8366829: Add constants for the Duration MIN/MAX values

[Pavel Rappo]

We have [recently discussed][] a possibility of adding the `Duration.MIN` and `Duration.MAX` constants. Can we now start implementation? If and when we are in agreement on this PR, I will file a CSR.

I drafted a minimal specification and added some tests. I tried to phrase the spec for `Duration.MIN` in a way that makes it clear that `Duration.MIN` is the most negative value and not the least positive.

[recently discussed]: https://mail.openjdk.org/pipermail/core-libs-dev/2025-September/151098.html

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Commit messages:
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/27534/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27534&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366829
  Stats: 55 lines in 3 files changed: 52 ins; 1 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27534.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27534/head:pull/27534

PR: https://git.openjdk.org/jdk/pull/27534