Fix Babel compilation error

The default Storybook Babel config did not recognize the `public`
keyword in our custom errors (e.g. `ExhaustivityCheckingError`
and `RedactableError`). To fix this, we can use Storybook's V7 mode to
supply a custom Babel config. This fixes the compilation error.

See: https://storybook.js.org/docs/react/configure/babel

extensions/ql-vscode/.babelrc.json

@@ -0,0 +1,16 @@
+{
+  "sourceType": "unambiguous",
+  "presets": [
+    [
+      "@babel/preset-env",
+      {
+        "targets": {
+          "chrome": 100
+        }
+      }
+    ],
+    "@babel/preset-typescript",
+    "@babel/preset-react"
+  ],
+  "plugins": []
+}

extensions/ql-vscode/.storybook/main.ts

@@ -12,6 +12,9 @@ const config: StorybookConfig = {
   core: {
     builder: "@storybook/builder-webpack5",
   },
+  features: {
+    babelModeV7: true,
+  },
 };
 
 module.exports = config;