Add Cloudflare wrangler files

Why is this change being made?

This MR contains the code for the Cloudflare worker that will handle the redirects for about.gitlab.com (and the review app) when we migrate from Fastly to Cloudflare.

I've got a single branch deployed via Cloudflare for testing purposes. Please test using the following URL:

https://add-cloudflare-wrangler.about.gitlab-review.app

Any other *.about.gitlab-review.app site will go via Fastly for the moment.

All redirects from data/redirects.yml should be working so please let me know if anything doesn't work correctly.

Related issue: https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/18945

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