Add/Refactor AdaptVQE tutorial

[kaelynj]

Closes #1167 and #1193

Was initially planning on first adding the tutorial and then refactoring the content, but after discussion needs to be refactored first before it can be merged.

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[kaelynj]

Tutorial is ready for review. I've done my best to outline the steps for converting the Hamiltonian to Paulis, but left the code untouched since it just uses what Mario wrote for the chemistry VQE tutorial.

The overall structure is to run through the full adapt-vqe loop once on a statevector simulator and then put everything together into a loop that runs within a single Session. (Note: the loop takes quite some time to run, just the gradient calculation takes about an hour of QPU time).

I also added in some functionality to save the results to a JSON file each time a job is finished in order to keep the intermediate results persistent in case the user's kernel dies. Let me know if this shouldn't be included.

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[frankharkins]

See inner-source for a continuation of this PR.