Unescape Markdown Escapes inside of a link

Fixes #14968

**Bug**
Due to https://github.com/chjj/marked/issues/829, markdown escapes inside of links are currently not rendered properly. This also can effect regular text that contains characters that are escaped when we convert them to markdown text.

**Fix**
For links, remove markdown escapes before rendering them.

src/vs/base/common/htmlContent.ts

@@ -71,6 +71,12 @@ export function textToMarkedString(text: string): MarkedString {
 	return text.replace(/[\\`*_{}[\]()#+\-.!]/g, '\\$&'); // escape markdown syntax tokens: http://daringfireball.net/projects/markdown/syntax#backslash
 }
 
+export function removeMarkdownEscapes(text: string): string {
+	if (!text) {
+		return text;
+	}
+	return text.replace(/\\([\\`*_{}[\]()#+\-.!])/g, '$1');
+}
 
 export interface IHTMLContentElement {
 	/**