Cannot use arrow keys to go to toggle icon in notebook find widget

1. Open a notebook and CTRL+F
2. Use tab on the find action buttons- notice that this allows you to navigate to all of the different buttons.
3. Use right/left arrow on the find action buttons- notice that this only loops between the first three.

I think the problem is here: https://github.com/microsoft/vscode/blob/a984153d6a98fba04f0a39a5ab9918c7b6e47511/src/vs/base/browser/ui/findinput/findInput.ts#L170-L194

The arrow key navigation is fixed at the findInput level, and we aren't adding to it, even when adding the funnel icon.

In this screencap, I accidentally press the down key-- that's not part of the demo 😅 https://github.com/microsoft/vscode/assets/31675041/9949cd63-a57c-42e3-9fd8-0d03de6f44cb