Hover / Suggest inconsistency: Plaintext Linkifying

[octref]

Split from #78718:

Plaintext Linkifying

const markupContent: MarkupContent =  {
	kind: 'plaintext',
	value: 'https://code.visualstudio.com'
};

[octref]

I think this should be done together with consideration for #79840. If for that we switch completion item details to use MarkdownString.appendText, this will be auto-fixed.

[octref]

@jrieken Do you think we should linkify the links in plaintext by doing that in appendText?

[jrieken]

This works when using the correct type: vscode.MarkdownString. The type above (its name) doesn't exist, the structure (ignoring the name) is verbatim/code blocks