For temporary alerts, replace static notification banners with toast notification

Description

The current static banner notifications are used in many different capacities. They are used to notify of important upgrades, tasks that need to be performed, and when an action is a success or a failure. These messages persist and are not dismissable, taking up valuable real estate.

Proposal

Replace user-action based notification banners (success, error, etc.) with toast notifications. Users will have the ability to dismiss the notification before it fades. This dismissal should persist in the database so it is never shown again.

Links / references

Documentation blurb

Overview

Toasts are an unobtrusive window element intended to display brief, auto-expiring bits of information to the user.

Use cases

Temporary notifications, user-action feedback.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.

• Feature assurance
• Documentation
• Added to features.yml