Support `//lang=graphql`

[Rekkonnect]

Unofficially there is a feature in VS syntax highlighting that supports //lang=xyz comments and highlights the string in the following line accordingly, like variables or string literals.

Some working examples for C#-test:

        // lang=C#-test
        var cstest = "var x = y;";

        Method(
            "value",
            // lang=C#-test
            "var x = y;",
            "value"
        );

        // lang=C#-test
        Method(
            "var x = y;",
            "var x = y;",
            "var x = y;"
        );

This can be picked up from the extension in a similar fashion and highlight GraphQL strings without relying on the target string receiver being properly annotated, which supports some edge cases.

[gianvitodifilippo]

Good suggestion. Unfortunately, this library is not currently actively maintained, but this will be an easy addition should development resume.