Feature Overview 

As a user of RHDH, I want to see Backstage's notifications so that I can be informed about asynchronous events from plugins and/or external services.

These plugins are core to the RHDH experience and should be part of our bundled plugins.

Bundled means they're still shipped as dynamic plugins, but part of our default released plugins.

Goals (aka. expected user outcomes)

RHDH and other plugins should be able to use the notification service

Requirements (aka. Acceptance Criteria):

see https://issues.redhat.com/browse/RHIDP-2042

all plugins in that feature request should be bundled.