"convert to a ES6 module" code action doesn't preserve type of quotes

[mjbvz]

microsoft/vscode#46679

TypeScript Version: 2.9.0-dev.20180327

Search Terms:

• Quick fix
• code action
• convert to es6 module

Code
For the js:

var path = require('path');

Run the Convert to es6 module code action

Expected behavior:
Quote style unchanged after conversion:

import path from 'path';

Actual behavior:
Quote style changed:

import path from "path";

[mjbvz]

Probably should fall under #20619