Add notification bell to show latest notification and link it with all notifications page

hypha/apply/activity/context_processors.py

hypha/apply/activity/templates/activity/notifications.html

hypha/apply/activity/views.py

hypha/settings/base.py

...rc/src/sass/apply/components/_activity-notifications.scss

hypha/static_src/src/sass/apply/main.scss

hypha/templates/base-apply.html

hypha/templates/includes/sprites.html