Add `focus-without-user-activation` permissions policy

### MDN URL

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Permissions-Policy

### What specific section or headline is this issue about?

_No response_

### What information was incorrect, unhelpful, or incomplete?

https://github.com/w3c/webappsec-permissions-policy/issues/273#issuecomment-2384287101. Since the issue is resolved, we should add the new permissions policy entry to MDN web doc.

### What did you expect to see?

add `focus-without-user-activation` permissions policy on https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Permissions-Policy.

### Do you have any supporting links, references, or citations?

The spec update PR: https://github.com/whatwg/html/pull/10672

### Do you have anything more you want to share?

_No response_