Test 28 - Syntax Highlight HTML

# Test 28 - HTML syntax highlight support

Each code block should be colorized by language class when syntax highlighting is enabled.

## Rust

    fn sum(a: i32, b: i32) -> i32 {
        let total = a + b;
        println!("{}", total);
        total
    }

## TypeScript

    interface InvoiceLine {
      sku: string;
      qty: number;
    }

    const line: InvoiceLine = { sku: "A-100", qty: 2 };
    console.log(line);

## SQL

    select customer_id, sum(total)
    from invoices
    where status = 'PAID'
    group by customer_id
    order by customer_id;