A Jupyter kernel for mlir (mlir-opt)

This is purely for experimentation. This kernel uses the reproducer runner conventions to run passes.

To install:

python3 -m mlir_opt_kernel.install

To use it, run one of:

    jupyter notebook
    # In the notebook interface, select MlirOpt from the 'New' menu
    jupyter console --kernel mlir

mlir-opt is expected to be either in the PATH or MLIR_OPT_EXECUTABLE is used to point to the executable directly.