Transform code base to typescript

Change-Id: Ia1f862fb5962ddd54b8d7643abbc39bb314d1f8e

src/App.test.tsx

@@ -0,0 +1,9 @@
+import { render, screen } from "@testing-library/react";
+import App from "./App";
+
+describe("App", () => {
+  it("renders", async () => {
+    render(<App />);
+    await screen.findAllByText("Welcome to Synapse-admin");
+  });
+});