Fix logout and root page loading dynamics

[Enet4]

Summary

• [webapp] Fix runtime error when trying to log out
  • It was a mistake in the retrieval of the router history object
• [webapp] Fix nuances of loading of root page when the user navigates to /#/ directly
  • Remove the loading page as an index route
  • Route to login page only after fetching from user store (even when there is no user session on local record)