v3 backport of #10938

This PR backports the fix for remote dev with Cloudflare Access to the v3-maintenance branch.

What changed

When using wrangler dev --remote with Cloudflare Access enabled on the preview service, the exchange API request was not including the Access token, causing authentication failures.

This fix acquires the Cloudflare Access token for the exchange URL hostname and includes it as a CF_Authorization cookie header in the fetch request. This mirrors the same Access token handling already present in the createWorkerPreview function for the prewarm request.

Review checklist

• Verify Access token is acquired for the correct hostname (switchedExchangeUrl.hostname)
• Confirm cookie header format is correct: CF_Authorization=${accessToken}
• Verify this doesn't break remote dev for users without Access (should be handled by the if (accessToken) check)
• Confirm this is an appropriate v3 backport (bug fix, not new feature)

• Tests
  • Tests included (inherited from original PR Fix remote dev with Access #10938)
• Wrangler E2E Tests CI Job required?
  • Required
• Public documentation
  • Documentation not necessary because: Bug fix that restores expected functionality

Link to Devin run: https://app.devin.ai/sessions/83395ce9848b417e892a334e552f0d6f
Requested by: @smacleod

Note: This PR should not be merged until the original PR #10938 is merged first (enforced by CI).