Plugins support for moving statements

[zardoy]

Is this request related to a problem? Please describe.

As I said in #493 with an example with 'css' prop it might be handy for developer to have an ability to move css classes when using css-in-js libraries.

There is an extension vscode-styled-components that provides completions and syntax highlighting. Extension similar to this can be used for handling that.

I think we can achieve this by exposing register method in this extension API. Then another extension can call abracadabraExt.exports.registerMoveHandler or something like that. I'd like to handle this.

[nicoespeon]

I think that's an interesting idea I'd like to dig into. Don't have time now, but I'll get back to this issue with more thoughts 👍