Integrate what's new in universal header bar

In order to have a way to tell people what has changed when it makes sense,

An icon is available in the universal header bar.
Clicking this icon opens a popup where I can see what's new, access the related doc when clicking a particular news, close the popup.
News are filtered:

• by component - I only see the ones for the component I'm in or the ones that don't have a component

News are ordered by priority DESC (i.e. higher priority first)