feat: add s390x and ppc64le support

[Nachiket-Roy]

Summary

This PR adds support for the s390x (IBM Z) and ppc64le (PowerPC 64-bit Little Endian) architectures to the jammy-tiny stack. It updates the stack definition (stack.toml), internal tooling (scripts/.util/tools.sh), and images.json to include these new architectures. It also extends the metadata and buildpack integration tests to verify successful builds for both platforms.

Use Cases

This change enables Paketo Buildpacks users to build, run, and deploy applications on IBM Z and PowerPC architectures using the jammy-tiny stack, expanding the platform compatibility footprint for multi-architecture deployments.

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Nachiket-Roy / name: Nachiket Roy (f5447a6)