[JS] GenerateStreamResponse.stream() should give me GenerateResponseChunks

[kevinthecheung]

Describe the bug
I get an iterable of GenerateResponseChunkData from generateStream but GenerateResponseChunk would be better.

To Reproduce

    const llmResponseStream: GenerateStreamResponse = await generateStream({
      prompt: `Suggest a complete menu for a ${subject} themed restaurant`,
      model: gemini15Flash,
    });

    for await (const responseChunk of llmResponseStream.stream()) {
      console.log(responseChunk.text()); // compiler error
    }

But if I add @ts-ignore before the line it compiles and works

Expected behavior

I want to use all of GenerateResponseChunk's useful methods. In fact I think it's required for partial structured output

Screenshots
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Runtime (please complete the following information):

• OS: [e.g. Linux, MacOS]
• Version [e.g. 22]

** Node version

• run node --version at paste here

Additional context
Add any other context about the problem here.