Consider returning window from openTestWindow

[jacobq]

Not that I'd want to encourage anyone to use @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 function in lib/test-support/index.js because it doesn't return a reference to the BrowserWindow 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