Make clippy URLs in popup clickable

[tmcguire]

When hovering over a clippy problem popup in vscode, I get something like the following screenshot:

It would be great if the URL, in this case https://rust-lang.github.io/rust-clippy/master/index.html#write_with_newline, was clickable, and clicking it would open it in a browser window. That would save time compared to the current workflow, which is to manually select the link with the mouse, copy it to the clipboard, open a browser and paste the URL into the browser.

(Thanks for implementing the applying the clippy suggestion as a quick fix, that's very useful!)

[kiljacken]

We can only show plain text in diagnostics currently, due to editor/LSP constraints. See also #4077

[Veykril]

This was implemented in #6585, the write_with_newline part in clippy(write_with_newline) is clickable since.