* Canonicalization pattern for eliminating identity ops
* Add a test for the identity elimination rule
* Remove frontend from test
* Use CHECK-NEXT instead of CHECK
* generate op from onnx document
* Restore FullGemm
* update the op attribute for shape inference and canonicalizer
* Update onnx_canonicalization.mlir
* Create and register ONNX Dialect with one Add operation.
* Fix file formatting.
* Change name from ONNX to SGIR.
* Use ONNX dialect. Change SGIR to frontend placeholder dialect.
* Add comments.
* Type clean-up.