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/models/Group.ts

@@ -0,0 +1,19 @@
+import BaseModel from "./BaseModel";
+
+class Group extends BaseModel {
+  id: string;
+
+  name: string;
+
+  memberCount: number;
+
+  updatedAt: string;
+
+  toJS = () => {
+    return {
+      name: this.name,
+    };
+  };
+}
+
+export default Group;