[ONNX] Fix linalg norm output's shapes and dtypes (#79506)
Part of #79263
This PR fixes the following matters:
1. Before this fix, the reduced output has `[1]` shape when `dim = None` and `keepdim = False`. Now the output is reduced to `[]` shape, which matches Pytorch's behavior.
2. Before this fix, the output is always casted to `Long`. Now the output is casted to the input's dtype.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/79506
Approved by: https://github.com/justinchuby, https://github.com/BowenBao
