RFR: 8355992: Add unsignedMultiplyExact and *powExact methods to Math and StrictMath [v2]

[fabioromano1]

On Fri, 2 May 2025 15:12:01 GMT, Raffaello Giulietti <rgiulietti at openjdk.org> wrote:

>> Add `powExact()` and `unsignedPowExact()` methods that operate on integer values arguments.
>> Further, add `unsignedMultiplyExact` methods as well.
>
> Raffaello Giulietti has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Clearer and more complete spec of the *pow* methods.

Some easy optimizations for special cases.

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Changes requested by fabioromano1 at github.com (no known OpenJDK username).

PR Review: https://git.openjdk.org/jdk/pull/25003#pullrequestreview-2812333652