Pass scope to `getKeyName` util function everywhere it's used

This will enable the helper to properly resolve object key names that use variables like:

```js
const FOO = 'some-property-name';
const obj = {
  [FOO] = 'hello world'
}
```

https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/067e8aa35d916e97e5091be3cd21f09ff00d77ed/lib/utils.js#L396