Run all does not guarantee in-order execution

[agoose77]

I noticed this today, and will take a look in due course.

This line ensures that a cell may not immediately execute if we're waiting for it to render. This would allow out-of-order execution. It's unfortunate that the current JupyterLab interface doesn't let us block during this time (e.g. if we could return a promise).

https://github.com/executablebooks/jupyterlab-myst/blob/6a9409e290a097166a4917cb67939e0ce91be1cd/src/actions.ts#L133

I think the solution will be to parse the MDAST separately to the render pass, i.e. keep a cached MDAST that invalidates if the model is changed. This would allow us to avoid waiting for the render event.

[agoose77]

Another thing to consider here is defining a custom executor that properly allows us to block during markdown-cell execution.