CN debugger: allow debugging of CN via Gillian

[kiranandcode]

This PR builds on #128 and ports it to work with the main branch of VERSE-toolchain.

[samcowger]

Unless you object, I'd like to base this PR on sc/cn-debug instead of main. It looks like it squashes that branch, as well as whatever changes you've made to it, into a single commit, which makes it difficult to see what work you're hoping to merge in.

[kiranandcode]

Oh, yep, that makes sense.

[kiranandcode]

I rebased cn-debug onto main, and then added my changes in my branch on top of them @samcowger

[kiranandcode]

Added functionality to generate and dump state traces + filter lenses by whether the json files have been generated or not

[samcowger]

My apologies, I keep changing main out from under you! I'm going to rebase sc/cn-debug onto main myself, because there are some changes I'd like to make to organize it as a sibling dune project to cn-lsp and telemetry. I think that should make this PR smaller and easier to understand, and will help us focus on the functional changes you've made.

[samcowger]

I am surprised by how poorly GitHub seems to be handling this - I see that you've made changes to cn-lsp/lib/lenses.ml in 846377f, for example, so why on earth should the PR's diff show that as a completely new file?

At any rate - I forgot that cn-dap needs to build on OCaml 5.1.1. which throws a bit of a wrench into development and CI. I've been trying to maintain compatibility with 4.14.1, because that's what CN officially supports. In practice, though, I think it works fine on 5.1.1 and people use that to develop on it, so I'm going to open a PR to upgrade this repo's tools to 5.1.1 in support of getting this debugger merged in.

[kiranandcode]

oh, yep, sounds good, let me know once cn-debug is in a stable state and I'll rebase my changes onto it, and hopefully should produce a more coherent diff.