[infershape] should be able to set tensor shapes - inputs and others

[zhenhuaw-me]

infershape is not very useful if the input shapes are symbolics (dynamic shapes). If the user can set input shapes, it's more powerful:

• If set to static shapes, the shape of the model will be known.
• Even for symbolics, the user can update the input shapes.

The setup should be optional, and can extend to all the tensors in the model (excluding shape op related).

Interface should be something like below.

onnx infershape path/to/input/model.onnx path/to/output/model.onnx --tensor-shape t1:[d0,d1] t2:[d0,d1,d3]