add a test that verifies that NextResponse can be cloned (#37883)

This resolves #35573

I can't seem to reproduce the issue so I only created a unit test that verifies that it has the correct behavior.
@tavvy can you also check this PR out to see if it makes sense or not?

## Bug

- [x] Related issues linked using `fixes #number`
- [x] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

test/unit/web-runtime/next-response.test.ts

@@ -2,7 +2,7 @@
  * @jest-environment @edge-runtime/jest-environment
  */
 
-import { NextResponse } from 'next/dist/server/web/spec-extension/response'
+import { NextResponse } from 'next/server/web/spec-extension/response'
 
 const toJSON = async (response) => ({
   body: await response.json(),
@@ -44,3 +44,12 @@ it('automatically parses and formats JSON', async () => {
     body: '',
   })
 })
+
+it('can be cloned', async () => {
+  const fetchResponse = await fetch('https://example.vercel.sh')
+  const newResponse = new NextResponse(fetchResponse.body, fetchResponse)
+  expect(await newResponse.text()).toContain('Example Domain')
+  expect(Object.fromEntries(newResponse.headers)).toMatchObject({
+    server: 'Vercel',
+  })
+})