[Improvement] Screen Loading Effect

[ruichen199801]

Implement loading spinner or skeleton to improve user experience when the user is waiting for content to load.

[ruichen199801]

Add loading support for hooks:

• LoadingItem: fetchRestaurants, fetchReviews, fetchSavedRestaurants
• LoadingContainer: fetchRestaurant, fetchReviewer, fetchCurrentUser
• SkeletonItem: recommend

[ruichen199801]

We may consider adding loading effects for auth hooks and save hooks as well.

[ruichen199801]

Skeleton animation sometimes looks not smooth in mobile.

[ruichen199801]

62 Add loading effect for login and signup.