React Context / update Zustand

[xinaesthete]

Background

This refactors to use React Context, as a step towards allowing more of Avivator to be used as a library, as per #745

Change List

• Updated Zustand; may need review if there are issues with associated upgrade of React to 18. Would perhaps have been better to do this separately to reduce noise in this PR (various warnings from Zustand have also been addressed).
• Adapt stores to use context API
  • An <AvivatorProvider> is used in index.jsx
  • export const useXxxStore = create(...) becomes const createXxxStore = () => createStore(...), with corresponding use declarations further down. I think this change looks bigger in diff than it might otherwise because of prettier formatting.
  • new hooks for useXxxStoreApi have been added, which access the context and return a reference to the given store. This is used by new versions of the useXxxStore hooks (which also wrap useStoreWithEqualityFn as per deprecation warnings from Zustand), as well as anywhere that useXxxStore.setState(...) was previously used, as it's not possible to determine which context should be used outside React rendering (event callbacks etc).

To the best of my knowledge this doesn't impact functionality or performance - pretty sure the current pattern doesn't incur any extra renders or unnecessarily expensive Zustand calls, but I could be mistaken.

I've run tests/lint etc as well as manually testing most features in the Avivator UI.

Checklist

• [x] Update JSdoc types if there is any API change. n/a?
• [x] Make sure Avivator works as expected with your change.

[ilan-gold]

@xinaesthete We will accept the PR. I will review soon.

[xinaesthete]

Another thing you might want to check as you review is whether the 'equality function' stuff looks right & isn't applied in the wrong way anywhere. That part of the PR was because of Zustand warnings but I suppose could be a place where there's potential for me to've done something sub-optimal, or that might need to change yet again with subsequent Zustand update (https://github.com/pmndrs/zustand/discussions/1937). Anyway, if anything does need to change now or in future, it will be in a very focused part of the code I believe.