More markdown effects with shiki transformers

```ts
const message = 'Hello World'
console.log(message) // prints Hello World
```

const message = 'Hello World'
console.log(message) // prints Hello World

```ts
console.log('Not focused');
console.log('Focused') // [!code focus]
console.log('Not focused');
```

console.log('Not focused');
console.log('Focused') // [!code focus]
console.log('Not focused');

```ts
console.log('No errors or warnings')
console.error('Error') // [!code error]
console.warn('Warning') // [!code warning]
```

console.log('No errors or warnings')
console.error('Error') // [!code error]
console.warn('Warning') // [!code warning]