This PR fixes an issue where the Assistant patch block was not being
rendered when using "Suggest Edits".

The issue was that the `BlockContext` already has a borrow of the
`Window`, so we can't use `update_in` to reborrow the window.

The fix is to reuse the existing `&mut Window` reference from the
`BlockContext` so we don't need to `update_in`.

Closes #24169.

Release Notes:

- Assistant: Fixed an issue where the patch block was not being rendered
when using "Suggest Edits".

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Co-authored-by: Max <max@zed.dev>