Enable React strict mode

This enables React strict mode which will print extra warnings to the
console when we use certain constructs incorrectly. This does not affect
production builds.

See https://beta.reactjs.org/reference/react/StrictMode

extensions/ql-vscode/src/view/webview.tsx

@@ -1,4 +1,5 @@
 import * as React from "react";
+import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
 import { vscode } from "./vscode-api";
 
@@ -27,10 +28,12 @@ const render = () => {
   const view: WebviewDefinition = require(`./${viewName}/index.tsx`).default;
 
   createRoot(element).render(
-    // Post a message to the extension when fully loaded. See https://github.com/reactwg/react-18/discussions/5 ("What about the render callback?")
-    <div ref={() => vscode.postMessage({ t: "viewLoaded", viewName })}>
-      {view.component}
-    </div>,
+    <StrictMode>
+      {/* Post a message to the extension when fully loaded. See https://github.com/reactwg/react-18/discussions/5 ("What about the render callback?")*/}
+      <div ref={() => vscode.postMessage({ t: "viewLoaded", viewName })}>
+        {view.component}
+      </div>
+    </StrictMode>,
   );
 };