Load host FFI libraries for Mac Catalyst tests

[fhasse95]

This PR adds support for loading macOS host FFI dylibs during Robolectric test runs launched from Mac Catalyst XCSkipTests.

Since Mac Catalyst test bundles cannot provide native libraries directly to the macOS JVM used by Robolectric, the harness pass a host library directory via SKIP_FFI_LIBRARY_PATH, and skip-ffi uses that path before falling back to the existing behavior.

Related PRs:

• Support XCSkipTests under Mac Catalyst skip#724
• Support XCSkipTests under Mac Catalyst skipstone#265

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• AI was used to generate or assist with generating this PR. Please specify below how you used AI to help you, and what steps you have taken to manually verify the changes.

AI was used to help identify the Catalyst/Robolectric host-library issue and draft the changes. Afterwards, I manually reviewed the code and verified the affected XCSkipTests from a Mac Catalyst test target.

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[marcprux]

Looks good. I presume it is expected to be on the user to manually set the correct SKIP_FFI_LIBRARY_PATH environment in their testing?

[fhasse95]

Looks good. I presume it is expected to be on the user to manually set the correct SKIP_FFI_LIBRARY_PATH environment in their testing?

It can technically be set manually by the user, but it’s primarily intended as an internal environment variable. The corresponding setup is part of skiptools/skip#724, where SKIP_FFI_LIBRARY_PATH is set automatically to the macOS host build output directory when running Robolectric tests for Mac Catalyst targets.