Upgrade to typescript 5.4.3

This PR makes all packages share the same typescript version and updates us to 
latest versions of typescript, ts-node, typescript-eslint/eslint-plugin and 
typescript-eslint/parser. 

I also noticed that the tsconfig we were extending (node18-strictest) was 
deprecated, so I switched us over to one that's more up to date. 

Also had to make a couple of small changes to the playground so that continues 
to build correctly.