We weren't including Deno files in `tsc` typechecking, but we also weren't using any `deno` commandsthat typecheck.This introduces typechecking in CI and fixes resulting hidden errors.The JSON hack isn't great but really it's the whole "import a json and write new data to it" patternthat should be simplified to "just read the new data in memory", since there's no actual reason towrite it to disk if you follow the code paths. It was just done that way because it was the shortestpath to add the dynamic fissue annotation from the previous implementation.

When building the package, we only care about vendoring `edge-runtime/` deps, but for Denotests/typechecking/linting, we want to vendor the deps of our build tools written in Deno too.