Notification presets

[rolfsmeds]

Describe your motivation

Notifications are highly configurable: you can set a theme variant, a duration, and a position. This is good, as it gives developers a lot of flexibility in creating the kinds of notifications they want. But it doesn't provide good out-of-the-box defaults for common types of notifications.

Describe the solution you'd like

A number of notification presets (vaguely similar to the notification types in Vaadin 8) that provide good default presets for common types of notifications:

Info

• Use case example: "New data available, click refresh to load it"
• Theme variant: default (light gray)
• Duration: 10 seconds
• Position: top-center

Success

• Use case example: "Process X finished succesfully"
• Theme variant: success (green)
• Duration: 5 seconds
• Position: bottom-center

Warning

• Use case example: "Your session will expire in 5 minutes"
• Theme variant: warning (yellow)
• Duration: persistent (non-auto-hiding)
• Position: top-center

Error

• Use cases example: "Something went wrong"
• Theme variant: error (red)
• Duration: persistent (non-auto-hiding)
• Position: center
• Should probably also be set to assertive

Describe alternatives you've considered

No response

Additional context

Would be nice if these presets were globally configurable somehow, but that can be a later enhancement, as these hardcoded presets will in no way affect existing applications or prevent the level of configurability we have today.

[rolfsmeds]

Actually bundling theme variants like this might be problematic since they are theme-specific: currently only the Lumo theme has them; Material has none and the application might be using neither (although that would be rather niche).