Factor EvalDescriptor out of SamplesDescriptor, improve JSDoc type annotations and more

[andrei-apollo]

This PR contains multiple non-user-visible changes to Inspect view. It is mostly (but not entirely) a subset of #911.

The only substantial change is factoring EvalDescriptor out of SamplesDescriptor. The EvalDescriptor is computed once per eval and contains information that doesn't change with the selected score. The SamplesDescriptor is now focused on data that depends on the selected score. I find that this separation improves readability, it should make caching better, and it is required for the fancy filter which doesn't depend on the selected score.

This PR also contains a lot of new JSDoc type annotations and type fixes.

Finally, it adds a prettierrc to ensure that per-user prettier settings don't break formatting.

---

Bonus pro-tip.

With all type errors fixed, it is now possible to enable type checking globally (not just in the open files) in VSCode/Cursor. I did this locally by creating a VSCode workspace file, inspect-ai.code-workspace, with the following content:

{
  "folders": [
    {
      "path": "."
    }
  ],
  "settings": {
    "typescript.tsserver.experimental.enableProjectDiagnostics": true
  }
}

Unfortunately, there is catch. We still have type errors in the generated files, and the TS plugin doesn't allow to exclude paths from type checking. So now I'm permanently using this error filter in VSCode:

!dist/*,!ansi-output.js,!tsconfig.json

Even with the filter, “Problems” counter includes these phantom errors, which is annoying, but when I navigate to the “Problems” tab, I only see real errors. Personally I find this to be an improvement, because I like global type checking. But I understand that this setup is far from ideal, so I'm not suggesting we enable it by default until I find a better way to suppress errors in generated files.

[dragonstyle]

Thank you for this! I'll have a look in detail tomorrow morning EST!

[dragonstyle]

A few suggestions - thanks again for the PR!

[dragonstyle]

This looks great to me, thank you! We're in the process of shipping an update to pypi and I'd like to wait until that has shipped to merge this (so we can get a few days / weeks testing internally before it goes to pypi). I'll merge it once we clear that release!

[andrei-apollo]

Sounds good to me.