Add initial support for AArch64 Linux guests on macOS platform

[Sangho Lee (sangho2)]

This PR implements a basic macOS userland platform and a runner to use the macOS platform with the Linux shim. It can run a hello-world ELF PIE binary with dynamic loading/rewriting.

[github-actions]

🤖 SemverChecks 🤖 ⚠️ Potential breaking API changes detected ⚠️

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--- failure enum_no_repr_variant_discriminant_changed: enum variant had its discriminant change value ---

Description:
The enum's variant had its discriminant value change. This breaks downstream code that used its value via a numeric cast like `as isize`.
        ref: https://doc.rust-lang.org/reference/items/enumerations.html#assigning-discriminant-values
       impl: https://github.com/obi1kenobi/cargo-semver-checks/tree/v0.50.0/src/lints/enum_no_repr_variant_discriminant_changed.ron

Failed in:
  variant AllocationError::AddressInUse 4 -> 5 in /home/runner/work/litebox/litebox/litebox/src/platform/page_mgmt.rs:227
  variant AllocationError::AddressInUseByPlatform 5 -> 6 in /home/runner/work/litebox/litebox/litebox/src/platform/page_mgmt.rs:229
  variant AllocationError::AddressPartiallyInUse 6 -> 7 in /home/runner/work/litebox/litebox/litebox/src/platform/page_mgmt.rs:231
  variant RemapError::OutOfMemory 4 -> 5 in /home/runner/work/litebox/litebox/litebox/src/platform/page_mgmt.rs:259