[lld] [lld][GNU Properties] Refactor storage of PAuth ABI core info (PR #141920)

[via llvm-commits]

sivan-shani wrote:

This PR is a **preparatory refactor** to support a follow-up patch that will add **AArch64 Build Attributes** to LLD. The intent is to split the work into clean, reviewable steps and avoid repeating past mistakes.

Specifically, this change isolates and simplifies the handling of GNU Properties, so that support for Build Attributes can later be added **on top of a clearer structure**, with minimal duplication and maximum alignment between the two.

We would appreciate **as many eyes as possible** on this PR to ensure it is solid and aligns with project expectations, especially after feedback on the previous attempt (PR #131990). This is the first step in a more structured and minimal series of changes.

https://github.com/llvm/llvm-project/pull/141920