C# delimiters for 3x, 4x and 5x double quotes are not string literals

[OnlineCop]

Bug Description

The default C# delimiter is @"..." (single quote string literal). The additional options currently show """...""", """"...."""", """""...""""" (3x, 4x, and 5x quote strings, but not string literals) when switching to them.

These other delimiter options should probably also be string literals.

Examples

1. @"..." delimiter:

   • REGULAR EXPRESSION: @""((?>[^""]+|[""]{2})*)""
   • TEST STRING: @"" @"text" @"a\nb" @"a""b" @"a\""\""b"
   • SUBSTITUTION: "$1"
   • Code Generator snippet:

         public static void Main()
         {
             string pattern = @"@[""]((?>[^""]+|[""]{2})*)[""]";
             string substitution = @"""$1""";
             string input = @"@"" @""text"" @""a\nb"" @""a""b"" @""a\""\""b""";

   • Result (in substitution field) on regex101: "" "text" "a\nb" "a""b" "a\""\""b"
   • Result (of "Code Generator" output) on try.dot.net: " @"text" "a\nb" "a"b" "a\"\"b"

2. """...""" delimiter:

   • REGULAR EXPRESSION: @""((?>[^""]+|[""]{2})*)""
   • TEST STRING: @"" @"text" @"a\nb" @"a""b" @"a\""\""b"
   • SUBSTITUTION: "$1"
   • Code Generator snippet:

         public static void Main()
         {
             string pattern = """
     @[""]((?>[^""]+|[""]{2})*)[""]
     """;
             string substitution = @"""$1""";
             string input = @"@"" @""text"" @""a\nb"" @""a""b"" @""a\""\""b""";

   • Result (in substitution field) on regex101: "" "text" "a\nb" "a""b" "a\""\""b"
   • Result (of "Code Generator" output) on try.dot.net (after manually prepending @ to """): " @"text" "a\nb" "a"b" "a\"\"b"

Expected

1. The delimiters should show @ before the """, """", """"".
2. The Code Generator output should as well. Additionally, there should probably not be a newline after the opening """ and before the closing """, as shown above.
   • I would expect it to look the way the @"..." outputs now.

[firasdib]

Thank you, fixed locally