[Feature Request] Rounded scroll bar

Context

• This issue is not a bug report. (please use a different template for reporting a bug)
• This issue is not a duplicate of an existing issue. (please use the search to find existing issues)

Description

Hi

I included the monaco editor in my website. But the website use modern style rounded scrollbars. Like this:

*::-webkit-scrollbar {
    width: 16px;
}

*::-webkit-scrollbar-track {
    border-radius: 8px;
}

*::-webkit-scrollbar-thumb {
    height: 56px;
    border-radius: 8px;
    border: 4px solid transparent;
    background-clip: content-box;
    background-color: #888;
}

*::-webkit-scrollbar-thumb:hover {
    background-color: #555;
}

It does no look good if the whole website has rounded scrollbars, but the editor has thick square ones. Can you please provide an option for rounded scrollbars?

Monaco Editor Playground Link

No response

Monaco Editor Playground Code

No response

The issue names no source files, tests, or playground link. Start by locating Monaco's existing scrollbar configuration and styling entry points, then determine how a rounded-scrollbar option should be exposed and verify it in a browser; done means the editor supports rounded scrollbars without changing the default appearance.