Completion item color is not extracted from documentation property when it is a MarkdownString

[bradlc]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.76.0-insider
• OS Version: macOS 12.5.1

Steps to Reproduce:

1. Clone https://github.com/bradlc/vscode-completion-issue
2. Open the extension in VS Code and run the "Run Extension" task from the "Run and Debug" panel
3. Create a new untitled file and change the language to "HTML"
4. Run the Trigger Suggest command or start typing "example" to reveal the "example" completion items
5. Notice that one of the completion items has a red block and one does not

Expected Behaviour:

Both completion items should display a red block.

Suggested Fix:

When the color extractor checks the documentation property it should account for MarkdownString values:

vscode/src/vs/editor/contrib/suggest/browser/suggestWidgetRenderer.ts

Lines 48 to 54 in eb940a2

	if (typeof item.completion.documentation === 'string') {
	const match = ColorExtractor._regexRelaxed.exec(item.completion.documentation);
	if (match && (match.index === 0 || match.index + match[0].length === item.completion.documentation.length)) {
	out[0] = match[0];
	return true;
	}
	}

For example the piece of code above could be changed to the following:

if (item.completion.documentation) {
  const documentation = typeof item.completion.documentation === 'string'
    ? item.completion.documentation
    : item.completion.documentation.value;
  const match = ColorExtractor._regexRelaxed.exec(documentation);
  if (match && (match.index === 0 || match.index + match[0].length === documentation.length)) {
    out[0] = match[0];
    return true;
  }
}