chore: Move to Typescript (#2783)

This PR moves the entire project to Typescript. Due to the ~1000 ignores this will lead to a messy codebase for a while, but the churn is worth it – all of those ignore comments are places that were never type-safe previously.

closes #1282

shared/utils/urls.ts

@@ -0,0 +1,5 @@
+const env = typeof window !== "undefined" ? window.env : process.env;
+
+export function cdnPath(path: string): string {
+  return `${env.CDN_URL}${path}`;
+}