Add title support for code blocks

[Mister-Hope]

Clear and concise description of the problem

It would be great if people can set a file name for code blocks, e.g.

```js [.vuepress/config.js] {1,3}
const a = 1;

console.log(“hello world”)
```

Suggested solution

Above

Alternative

No response

Additional context

No response

[nimonian]

Seconded, I would love this too. Perhaps, when the title is provided, it could replace the language name that appears in the top right?

[Mister-Hope]

PR welcomed for this. It would be great if you could help.

[nruffing]

I can help with this if you would like to assign this to me. I like the the idea of of being able to specify text to override the displayed language name, especially for setting it to a filename.