Remove `noUnusedLocals` option from `tsconfig.json` files. It's redundant, as Oxlint `no-unused-vars` covers this for us.
It's an annoyance to have `noUnusedLocals` enabled, as in VS Code TypeScript complains about unused vars, even if they're prefixed with `_`.
Removing this option allows simplifying type tests added in #20066. Only reason these types had to be exported was to stop TS complaining that they were unused.
Replaces #20064
The `dom` lib was implicitly being injected, this means stuff like `Token` and `Comment` were in the global scope, which was incorrect.
cc @overlookmotel