[FEATURE]: Add TypeScript definitions for custom bundles

Since plotly.js v4 includes built-in TypeScript definitions, it would be great if custom bundles could also generate matching TypeScript definitions.

This would make custom bundles safer and easier to use in TypeScript projects.

In my case, I sometimes use a custom bundle to test newly developed features before they are released. However, the custom bundle does not include corresponding type definitions, so I have to rely on the types from the latest released version.

This can lead to missing or mismatched types, especially when the custom bundle includes new APIs or features that are not yet available in the released version.

まず、カスタムバンドルがどのように生成され、組み込みの TypeScript 定義が plotly.js v4 にどのように含まれているかを追跡します。未リリースの機能の API を含め、カスタムバンドルで期待される一致する出力を定義し、生成された定義がバンドルを反映していることを検証します。