Improve `app.quit()` calls

[joaomoreno]

Due to moving the shared process to a window.

Currently, electron-main/main.ts detects that when there are no more workbench windows open, and not on macOS, it disposes the shared process, which closes its window, which fires the all-windows-closed event, which triggers app.quit().

The windows service should be the one responsible for this:

• It should detect that no more workbench windows are open, not on macOS, and call ILifecycleService.quit()
• the LifecycleService should be the single point of app.quit() calls

[joaomoreno]

To keep the number of issues in our inbox on a manageable level, we're closing issues that have been on the backlog for a long time but haven't gained traction: We look at the number of votes the issue has received and the number of duplicates issues filed.

Thanks for your understanding. Happy coding!