story: alert should have same fade out animation on close as notification

[jeripeierSBB]

No description provided.

[TomMenga]

I have a couple of questions/topics to discuss:

1. In the current implementation, the alert has no close API. When clicking the closing button, it just emits a requestDismissal. Proposal:

• remove the requestDismissal event
• Add a cancellable willClose and a didOpen event
• Expose a close method that will be called automatically when clicking the closing button (as the sbb-notification)

2. The animation property type default change from open to all (as the sbb-notification)

These changes would both generate a breaking change