RFR: 8334717: Add JVMCI support for APX EGPRs [v2]

[Doug Simon]

On Tue, 20 May 2025 06:14:09 GMT, Yudi Zheng <yzheng at openjdk.org> wrote:

>> This PR marks extra general purpose registers introduced by Intel APX as Graal allocatables. It also drops AMD64/AArch64/RISCV64.flags and RegisterArray
>
> Yudi Zheng has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix tests

Marked as reviewed by dnsimon (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/23159#pullrequestreview-2856879701