[Feature request] Add method to restore previously removed range

[aleclarson]

const string = new MagicString("abcd")

string.remove(0, 3)
string.toString() // => "d"

// ...later on...
string.restore(2, 3)
string.toString() // => "cd"

[aleclarson]

Why not just insert the removed range with existing methods?
Because then I wouldn't be able to insert new content into the restored range.

👉 Example: https://stackblitz.com/edit/node-1gmfpo?file=index.js (backup gist)

[antfu]

That makes sense to me. PR welcome :)

[KermanX]

I opened #271 for this feature.

The method introduced in that PR is reset, rather than restore, because of its actual behavior