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/utils/__mocks__/ApiClient.ts

@@ -1,6 +1,6 @@
 /* eslint-disable */
 export default {
   client: {
-    post: jest.fn(() => Promise.resolve),
-  },
-};
+    post: jest.fn(() => Promise.resolve)
+  }
+};