RFR: 8357913: Add `@Stable` to BigInteger and BigDecimal [v4]

[Chen Liang]

On Wed, 4 Jun 2025 13:12:33 GMT, Shaojin Wen <swen at openjdk.org> wrote:

>> Some static final arrays of BigInteger and BigDecimal are stable and immutable. We should add `@Stable` to give the optimizer more information
>
> Shaojin Wen 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 five additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'upstream/master' into math_stable_202505
>  - BigInteger::mag remove Stable
>  - bug fix, from @minborg
>  - BigInteger::mag add `@Stable`
>  - add stable

Looks okay to me

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

Marked as reviewed by liach (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/25437#pullrequestreview-3035674378