test(amazonq): add mock for IntersectionObserver (#6867)

## Problem
`ReferenceError: IntersectionObserver is not defined` in E2E tests due
to JSDOM


## Solution
Add mock for IntersectionObserver

---

- Treat all work as PUBLIC. Private `feature/x` branches will not be
squash-merged at release time.
- Your code changes must meet the guidelines in
[CONTRIBUTING.md](https://github.com/aws/aws-toolkit-vscode/blob/master/CONTRIBUTING.md#guidelines).
- License: I confirm that my contribution is made under the terms of the
Apache 2.0 license.

Author: avi-alpert

packages/amazonq/test/e2e/amazonq/framework/jsdomInjector.ts

@@ -47,4 +47,17 @@ export function injectJSDOM() {
 
     // jsdom doesn't have support for structuredClone. See https://github.com/jsdom/jsdom/issues/3363
     global.structuredClone = (val: any) => JSON.parse(JSON.stringify(val))
+
+    global.IntersectionObserver = class IntersectionObserver {
+        observe() {}
+        unobserve() {}
+        disconnect() {}
+        takeRecords() {
+            return []
+        }
+        // eslint-disable-next-line unicorn/no-null
+        root = null
+        rootMargin = ''
+        thresholds = []
+    }
 }