[Web] Render basic set of notification items

[exalate-issue-sync]

Description

User Stories

• As a user who receives a notification, I want to see dedicated information that is specific to the notification type so that I can quickly understand the notification (because my brain categorized it).

• As a user who receives a notification, I want to click on it so that I don't need to search for the file in the file tree.

Value

Acceptance Criteria

• following notifications can be rendered in the dropdown that appears when clicking on the notification bell:
  • "[User] shared [Resource] with you"
  • "[User] unshared [Resource] with you"
  • "[User] added you to Space [Space Name]"
  • "[User] removed you from Space [Space Name]"
  • "[User] disabled Space [Space Name]"
  • "[User] deleted Space [Space Name]"
  • "Access to [Resource] expired"
  • "Virus found in [Resource]. Upload not possible. Virus: [Virusname]"
• for this first iteration:
  • no translations. only render text like it comes from the backend.
  • events don't resolve to resources. only implement the actions coming from the backend (e.g. accept/decline share).
• notifications bell in the topbar shows an overlay with the number of notifications in a red circle (see GhostElement component in design system for overlay). If more than 99 notifications exist, show 99+ in the red circle.
• refactor vuex store code away and move it into the Notifications component
• Note - not part of this story: Notifications can be configured in the user settings to show notifications for more events (not part of this story). Events table: https://confluence.owncloud.com/display/PROD/Notifications#Notifications-Events
• Note for reference: available notification types in the backend: https://github.com/cs3org/reva/tree/edge/pkg/events
• Note rich Notifications: https://github.com/nextcloud/notifications/blob/master/docs/ocs-endpoint-v2.md

Definition of ready

[ ] everybody needs to understand the value written in the user story
[ ] acceptance criteria has to be defined
[ ] all dependencies of the user story need to be identified
[ ] feature should be seen from an end user perspective
[ ] user story has to be estimated
[ ] story points need to be less then 20

Definition of done

• Functional requirements
  [ ] functionality described in the user story works
  [ ] acceptance criteria are fulfilled
• Quality
  [ ] code review happened
  [ ] CI is green
  [ ] critical code received unit tests by the developer
  [ ] automated tests passed (if automated tests are not available, this test needs to be created and passed
• Non-functional requirements
  [ ] no sonar cloud issues