"@" character followed by double quote containing string escapes content within the string in Markdown

Summary

The quoted user mention syntax causes incorrect escaping in code blocks that occur in:

• pull request comments
• pull request description
• Markdown (md) files

Steps to Reproduce

1. Add the following text to one of the following:

• pull request comments
• pull request description
• Markdown (md) files

```cs
var s1 = "c:\test\\zoo\\";
var s2 = @"c:\test\bar\\baz";
```

The specific sequence of characters required to experience this behaviour is the 'at' symbol followed by a double quote and some content that contains backslashes e.g. @"hello\world"

Expected Results

The text is displayed in the following way:

var s1 = "c:\test\\zoo\\";
var s2 = @"c:\test\bar\\baz";

Actual Results

The text is displayed like this:

Pull request comment

Pull request details

Markdown file

Workaround

If it is acceptable to use single quotes, surrounding the string following the @ with single quotes will prevent this from occurring. 

It is also possible to double-escape the backslashes, however note that once this bug is fixed, that double escape will likely no longer apply.