Feat/persist inline results

[xgdgsc]

Fixes #2705

I' ve encountered too many performance issues with jupyterlab and decided to do it with vscode.

[davidanthoff]

Hm, I have to admit that I'm not really convinced that we should have something like this in the extension.

For one, this seems a very ad-hoc system to persist Julia session state, that to me seems feature creep for the extension. In particular, it seems to me that while a generic session persistence feature might be nice, it should be implemented outside of the extension. I also just remember a lot of attempts to address this in some systematic way in the past in packages, none of the really worked out long-term, which suggests to me that this is a fairly tricky problem to solve well.

A second thing is that the saving of location information seems very brittle? A simple edit of the source file with some other editor would screw everything up, right?

And third, I'm also not really convinced that storing session state next to source files is a good idea...

Sorry to be so negative, but this is a pretty large-scale feature, and we are generally careful before we add something like this. Hope you understand! I'm also curious to hear what @pfitzseb thinks about this.

[xgdgsc]

Implementation details could be discussed. I just need this to do my work for very long analysis notebooks where jupyterlab becomes unusable slow.
The use case is I would never edit the file with another editor.
I don' t find file next to source file very bad because I' m used to using jupytext to sync ipynb to plain py/jl/md files. Deleting the file to reset is easy and obvious.

[xgdgsc]

Added cleanup on start of loading persistent when code hash not matching. Added plot matching selection as fix #2503 (also works without persistent) . Added persistent of plots.