[Feature Request] Create collapsed and expanded elements in tooltips

### Description I try create my own extension. I use vscode api extensions. But I didn't find any methods for create collapsed / expanded elements in tooltip > I try found any methods with keywords: `collapse`, `collapsed` etc. I found only **treeItems**, but I think this is other. **So, I want create request to add this ability to api (if this is already exist) or create method for it.** ### Example How we can know, vscode have debug mode. If we enable it and try use **breakpoints**, we can check what storage in variables (or etc) Example:  How we can see, `_proto_`, can be **expanded**/**collapsed** on click:  ### Suggestion So, how I will be wrote up. Now, we can create tooltips with **markdown string** or **string** But I want create a bit more, like this "spoilers" (expanded / collapsed elements), > if we can I want use highlight too (like change color, bold and other styles) for any created elements. Not like a code block.