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

app/hooks/useUnmount.ts

@@ -0,0 +1,14 @@
+import * as React from "react";
+
+const useUnmount = (callback: (...args: Array<any>) => any) => {
+  const ref = React.useRef(callback);
+  ref.current = callback;
+
+  React.useEffect(() => {
+    return () => {
+      ref.current();
+    };
+  }, []);
+};
+
+export default useUnmount;