Add ONNX support and Benchmarks

What's Changed

• Preserve symlinks in CI by @tkoskela in #359
• Make sure ORT lib location is known to cmake by @20DM in #358
• Fix bugs in examples by @tkoskela in #357
• ONNX Testing by @mmcleod89 in #343
• Remove spdlog reference from README by @20DM in #361
• Move models out of data and install them when onnxrt is on by @tkoskela in #369
• Enable ONNXrt in the CI by @20DM in #368
• Remove the notinstalled data namespace since data is being installed by @tkoskela in #370
• Use non-greek sopt interface by @mmcleod89 in #371
• add Homebrew lib dir to lib path by @20DM in #372
• Update benchmarks by @tkoskela in #367
• Update changed benchmark file name in CmakeLists by @tkoskela in #374
• Rename nu and gamma in padmm examples by @tkoskela in #377

Full Changelog: v4.2.0...v5.0.0