Switch to isolated declarations for faster builds

[kenotron]

This is a small repo, so it isn't strictly necessary. However, isolated declarations is giving us a 14.59s -> 5.43s improvement in typechecking. This change includes the following:

1. added an isolated-declarations flag to the main tsconfig.json: this means no allowJS
2. replacing the type check step from using a tsc worker to simply using tsc processes
3. adjusted the lage pipeline config to allow fastest parallelized builds possible.

[ecraig12345]

I merged the explicit module boundary type changes and typescript update separately, since those are good to have regardless of TS settings. But I'm confused about some aspects of the remaining changes:

• Even with the tsconfig in Ken's original change, it doesn't have the settings noEmit or emitDeclarationOnly. So the "types" command (which now runs types as specified by each package, usually monorepo-scripts tsc) is actually transpiling/emitting too.
• There's zero documentation I could find of the SWC setting experimental.emitIsolatedDts--maybe it was discussed on social media that's not indexed?? I found some related issues, so apparently a few people are using it, but I'm hesitant without knowing more about the behavior/implementation and limitations.