Feature Request: Support declarative web push

[AlexGustafsson]

User stories

• As a user I want to receive notifications when updates are available

Feature description

By using "declarative web push" proposed by WebKit we can rather easily support nice push notifications to users. The same server-side API could be used to support third-party integrations.

See: https://github.com/WebKit/explainers/blob/main/DeclarativeWebPush/README.md

[AlexGustafsson]

Right now, only Safari Technology Preview supports declarative web push. It does not seem to be connected to a push service, though. You'll get a request to allow push messages, but the promise never resolves.

Test.

let button = document.createElement('button')
document.body.appendChild(button)
button.onclick = () => {
pushManager.subscribe({userVisibleOnly: true, applicationServerKey: "BNEAYHIBammqknCovdHsGz9ORczAYsJ__povyj2TKTkBeVULYs9DDC3c-wNHGOiY6fijxHfcfL1Cw8BY758ch-c"})
}
button.style = "width: 100px;height: 100px;background-color: red;"

Unhandled Promise Rejection: AbortError: Connection to web push daemon failed