Consider returning `window` from `openTestWindow`

Not that I'd want to encourage anyone to use [`@electron/remote`](https://github.com/electron/remote), but I still have code that uses it so need to do stuff like: `require('@electron/remote/main').enable(someWindow.webContents);`

In the case of an `ember-electron` app's tests, this means I can't use the default [`openTestWindow`](https://github.com/adopted-ember-addons/ember-electron/blob/main/lib/test-support/index.js#L32) function in [`lib/test-support/index.js`](https://github.com/adopted-ember-addons/ember-electron/blob/main/lib/test-support/index.js) because it doesn't return a reference to the [`BrowserWindow`](https://www.electronjs.org/docs/latest/api/browser-window) it creates. It's not really a big deal in that it's not hard to work around, but if you'd be open to a PR that changes this I'd be willing to make one. (And it'd let me reduce some duplication on my side.)

See also:

* https://stackoverflow.com/questions/69233435/uncaught-error-electron-remote-is-disabled-for-this-webcontents
* https://stackoverflow.com/questions/69059668/enableremotemodule-is-missing-from-electron-v14-typescript-type-definitions
* https://github.com/electron/remote#migrating-from-remote