Convert markdown to normal xml

[carlossanlop]

We don't want to backport markdown to triple slash. Convert it back to normal xml.

[carlossanlop]

We have functions that do this task:

api-docs-sync/src/PortToTripleSlash/src/libraries/RoslynTripleSlash/TripleSlashSyntaxRewriter.cs

Lines 922 to 990 in cc8e3e8

	private static XmlNodeSyntax GetTextAsFormatCData(string text, SyntaxTriviaList leadingWhitespace)
	{
	XmlTextSyntax remarks = GetTextAsCommentedTokens(text, leadingWhitespace, wrapWithNewLines: true);
	XmlNameSyntax formatName = SyntaxFactory.XmlName("format");
	XmlAttributeSyntax formatAttribute = SyntaxFactory.XmlTextAttribute("type", "text/markdown");
	var formatAttributes = new SyntaxList<XmlAttributeSyntax>(formatAttribute);
	var formatStart = SyntaxFactory.XmlElementStartTag(formatName, formatAttributes);
	var formatEnd = SyntaxFactory.XmlElementEndTag(formatName);
	XmlCDataSectionSyntax cdata = SyntaxFactory.XmlCDataSection(remarks.TextTokens);
	var cdataList = new SyntaxList<XmlNodeSyntax>(cdata);
	XmlElementSyntax contents = SyntaxFactory.XmlElement(formatStart, cdataList, formatEnd);
	return contents;
	}
	private static string RemoveUnnecessaryMarkdown(string text)
	{
	text = Regex.Replace(text, @"<!\[CDATA\[(\r?\n)*[\t ]*", "");
	text = Regex.Replace(text, @"\]\]>", "");
	text = Regex.Replace(text, @"##[ ]?Remarks(\r?\n)*[\t ]*", "");
	return text;
	}
	private static string ReplaceMarkdownWithXmlElements(string text, List<DocsParam> docsParams, List<DocsTypeParam> docsTypeParams)
	{
	text = CleanXrefs(text);
	// commonly used url entities
	text = Regex.Replace(text, @"%23", "#");
	text = Regex.Replace(text, @"%28", "(");
	text = Regex.Replace(text, @"%29", ")");
	text = Regex.Replace(text, @"%2C", ",");
	// hyperlinks
	text = Regex.Replace(text, RegexMarkdownLinkPattern, RegexHtmlLinkReplacement);
	// bold
	text = Regex.Replace(text, RegexMarkdownBoldPattern, RegexXmlBoldReplacement);
	// code snippet
	text = Regex.Replace(text, RegexMarkdownCodeStartPattern, RegexXmlCodeStartReplacement);
	text = Regex.Replace(text, RegexMarkdownCodeEndPattern, RegexXmlCodeEndReplacement);
	// langwords|parameters|typeparams
	MatchCollection collection = Regex.Matches(text, @"(?<backtickedParam>`(?<paramName>[a-zA-Z0-9_]+)`)");
	foreach (Match match in collection)
	{
	string backtickedParam = match.Groups["backtickedParam"].Value;
	string paramName = match.Groups["paramName"].Value;
	if (ReservedKeywords.Any(x => x == paramName))
	{
	text = Regex.Replace(text, $"{backtickedParam}", $"<see langword=\"{paramName}\" />");
	}
	else if (docsParams.Any(x => x.Name == paramName))
	{
	text = Regex.Replace(text, $"{backtickedParam}", $"<paramref name=\"{paramName}\" />");
	}
	else if (docsTypeParams.Any(x => x.Name == paramName))
	{
	text = Regex.Replace(text, $"{backtickedParam}", $"<typeparamref name=\"{paramName}\" />");
	}
	}
	return text;
	}

but still need to confirm with detailed unit tests that it works as expected, especially for items that are not markdown standard like [!NOTE], [!IMPORTANT] and similar.

cc @smasher164