Use platform-specific CodeQL bundles

[mbaluda]

Summary

• download the upstream CodeQL bundle for the current host instead of the deprecated all-platform archive
• create, export, upload, and consume only the current platform's custom bundle through QLT_CODEQL_BUNDLE_PATH
• distinguish Linux x64 (linux64) from Linux ARM64 (linux-arm64)
• test platform selection on Linux x64, Linux ARM64, Windows, and macOS
• update generated workflows and action versions used by the affected checks

Why

GitHub deprecated codeql-bundle.tar.gz in CodeQL CLI 2.27.0 and plans to remove it in March 2027: https://github.blog/changelog/2026-09-22-deprecation-notice-all-platform-codeql-bundle/

Per-platform bundles avoid that deprecated archive and stop QLT from creating and exporting bundles for platforms other than the current host.

Linux ARM64 scope

This PR recognizes and tests the linux-arm64 selection on a native GitHub-hosted ARM64 runner. QLT packaging remains on released codeql-bundle 0.5.0 so CI and release builds use an available dependency.

End-to-end Linux ARM64 custom-bundle creation will require advanced-security/codeql-bundle#33 to merge and codeql-bundle 0.6.0 to be published, followed by a dependency bump here.

Validation

• dotnet test test/CodeQLToolkit.Shared.Tests/CodeQLToolkit.Shared.Tests.csproj
• actionlint .github/workflows/internal-pr-test-quick-bundle-creation.yml
• platform-selection jobs pass on ubuntu-latest, ubuntu-24.04-arm, windows-latest, and macos-15
• CodeQL test-matrix and unit-test-matrix generation pass with codeql-bundle 0.5.0

[mbaluda]

Once advanced-security/codeql-bundle#33 merges and v0.6.0 is released, #42 should bump the four remaining 0.5.0 packaging references and run an end-to-end custom-bundle test on ubuntu-24.04-arm.