[Google Search API] Expandable `buttons` not parsed on mobile

[btaunt]

We currently do not parse the expandable "buttons" in mobile view (with no knowledge_graph present). This works for some searches, which was fixed in https://github.com/serpapi/SerpApi/pull/4704

On desktop for the same search results, these items are pulled under knowledge_graph > buttons. In mobile searches, we do not render the knowledge_graph for this example, so unsure of the best place to render these items (which keys / naming to use).

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Playground (mobile) Playground (desktop)