Remove TypeScript DOM stdlib usage

[blaine-arcjet]

According to the node typescript type maintainers in https://github.com/DefinitelyTyped/DefinitelyTyped/pull/66824, people should never combine @types/node and the DOM types from the TS standard lib. However, the node types don't contain types for the WebAssembly global and they only exist in DOM, so we need to use them right now. However, the Headers type in @types/node conflicts with the Headers in DOM.

We should contribute the WebAssembly types (and any other we are relying on from DOM) to @types/node so we don't need the TS standard library.