Notifications UI : Better UX

Notification is a very important feature but it was not used because it has a very bad UX. At one time, Project Managers and SupaAgents may receive hundreds of notifications making it unusable. Our users have automatically ignored this feature so we have to do something about it.

Improved UX;
1. Grouped similar notifications together to remove redundancy
2. Relative timestamp for easier time data comprehension
3. Grouped notifications by categories, eg: Projects
4. Using scarcity principle to nudge Agents to join a project
5. Summarized multiple notifications into one dynamic notification
6. Provide the ability to opt-out and control notifications
7. Added empty state when there is no notifications at all