Enhancements to make it more Mac App Store (mas) compatible

- disable the autoupdater if running as mas (was not working anyway, just logging an error on every start)
- replace check via app.requestSingleInstanceLock() with LSMultipleInstancesProhibited in Info.plist
  due to https://github.com/electron/electron/issues/15958


- Quit the app also when all windows are closed to conform to macOS Human Interface Guidelines
  Comments from review:
  If the application is a single-window app, it might be appropriate to save data and quit the app when the main window is closed.
- "asarUnpack": "**/*.node" to also sign the native addons when packaging
- add the required mas-specific entitlements which include the app-sandbox key

Signed-off-by: Christoph Settgast <csett86@web.de>