Notification mechanism for Guardian

[anvabr]

Problem description

Currently the status of most long-running Guardian actions, such as minting tokens, publishing (potentially large) documents, is not visible thus users may get the wrong impression or get confused. Furthermore, these long-running operations usually involve 3rd party (external) systems, and thus error prone. When errors occur the users do not get notified about them, and may notice failures later in the process thus causing them to attribute the errors to the wrong step- usually their or the system last action.

Requirements

Introduce notification capability to Guardian such that users can see:

• the progress of long-running tasks (i.e. "policy creation is 70% complete")
• the status of completed tasks
• review all the tasks (perhaps navigating to the special page by clicking 'view all tasks')
• navigate into tasks to see the details about the tasks or other relevant info about the results of the task execution (e.g. created artifacts)

There should be a way to mark notifications as 'read' one by one or 'all'.

Add the capability into the policy to create notifications (i.e. a new 'notification block') which would enable policy creators to alert particular users about the actions they need to take and/or inform them about an event.

Definition of done

• Notification system is implemented where tasks list is accessible from the UI via a drop-down menu with the functionality as described above.
• Documentation updated accordingly.
• An example usage of the notification block is implemented in one of the demo policies.

Acceptance criteria

Users get access to the status information of at least the following long-running tasks:

• token creation
• token minting
• policy/shema create, import, export, publish, clone
• user and key operations