Make hideWindowOnQuit = true by default on macOS

Right now, this change doesn't do anything, because hideWindowOnQuit is ignored on macOS (see shouldHideWindowInsteadOfClose in app-window.ts).
In the future, if we wanted macOS users to be able to fully close the main window, we would need to remove the __DARWIN__ check from shouldHideWindowInsteadOfClose, and then it would make sense for the default value to be true.

Making this change now so that new installs start populating this setting with the correct value, reducing confusion in the long run.

Author: pol-rivero

app/src/lib/stores/app-store.ts

@@ -634,7 +634,7 @@ export class AppStore extends TypedBaseStore<IAppState> {
   private titleBarStyle: TitleBarStyle = 'native'
   private showRecentRepositories: boolean = true
   private showWorktrees: boolean = false
-  private hideWindowOnQuit: boolean = false
+  private hideWindowOnQuit: boolean = __DARWIN__
 
   private useWindowsOpenSSH: boolean = false