Can't render more than 100k characters of markdown in a chat response

[roblourens]

We have this restriction https://github.com/microsoft/vscode/blob/3d3e1b7e487a077f1a5d2bc5fb16d3278456cd8d/src/vs/base/browser/markdownRenderer.ts#L235-L237

We should try to do better with rendering really large markdown strings, like by periodically yielding and continuing in an async step.

https://github.com/microsoft/vscode/pull/213086#issuecomment-2122265148

This affects everywhere that markdown is rendered in vscode, but probably nowhere else typically wants to have this much markdown.

[Khahan1104]

New88