[FEATURE]: Provide an obvious way to access underlying data arrays within a Figure object (rather than the base64-encoded versions)

Hi, I have some some code here, as below (edited to remove extra logs). I'm converting a plotly figure into json, and then loading it with json loads. You would expect that to preserve the original data.

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However, as you can see, the "y" data (which had previously been an array of large numbers) are wrongly converted into this "bdata" thing instead.

I was able to solve this and get the data in the format I wanted by going from 6.0.1 -> 5.24.1, which was the last stable build I was using. I think this is a pretty fundamental issue, so let me know if there's anything else I can share.

从 Figure 对象的 JSON 转换路径入手，使用 json loads 重现报告的案例，并比较版本 6.0.1 和 5.24.1 的输出。追踪 y 数组变为 bdata 的原因，并将完成标准定义为提供一种无需 base64 编码即可访问原始底层数组的显而易见的方式。