[mlir] Add simple jupyter kernel

Simple jupyter kernel using mlir-opt and reproducer to run passes.
Useful for local experimentation & generating examples. The export to
markdown from here is not immediately useful nor did I define a
CodeMirror synax to make the HTML output prettier. It only supports one
level of history (e.g., `_`) as I was mostly using with expanding a
pipeline one pass at a time and so was all I needed.

I placed this in utils directory next to editor & debugger utils.

Differential Revision: https://reviews.llvm.org/D95742