onnxscript/ir code freeze

With https://github.com/microsoft/onnxscript/pull/2324, we are migrating to https://github.com/onnx/ir-py. All current diffs will be migrated to the onnx/ir-py repo and a v0.1.0 will be released. Development can continue on onnx/ir-py after the migration PR is merged.