feat: C# raw string literal

[jairbubbles]

• Support C# raw string literals (cf https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/tokens/raw-string)
• It starts by a minimum of three " and end by the same number of " and can span on mutliple lines

[jairbubbles]

@microsoft-github-policy-service agree

[vgallegob]

I would like to see this one added, it's a much better way to do literals.