Sunset old Squiggle versions
After all subtasks are implemented, we will be able to remove the dependency on old versions from versioned-components.
This is higher priority than I thought: when I filed this, I thought this is just to reduce the burden of maintaining complicated types in versioned-components.
Now I realize this task is also important for improving hub's complication times. I did some profiling of tsc, and it shows that versioned-components (squiggle-lang -> immutable.js chain in particular) is the slowest part.
Good find. It seems like we don't have too many old models, so hopefully those won't be too bad.
Where's a chance that something went wrong with our tsconfig files or with the last TypeScript version, btw, maybe with skipLibCheck option. I don't remember things being as bad as they're now.
Could be worth doing some Git Bisect or similar on.