Add support for Rust raw strings

[KernelKrusha]

Will match the following in .rs files:

let query = r#"--surrealql
    SELECT * FROM type::table($table);
"#;

or alternatively:

let query = r#"--surql
    SELECT * FROM type::table($table);
"#;

I have no idea what I am doing, but it works 😄

[rvdende]

I tried copying this and trying locally but cant get it to work. It seems vscode applies it for a second and then the rust syntax colours overrides it.

[musjj]

Why not match the style from JavaScript, like this:

let query = /* surrealql */ r#"
SELECT * FROM type::table($table);
"#;