Integrate Umami message

@ckrina:
demo_umami.profile does this by choosing to add a hook_toolbar (in the .profile). this item uses an inline_template build simply add the link and add a library to style it.

i might think this could be an menu block added thru Unami itself rather than something navigation needs to provide.

@SKAUGHT this is a message we have designed. It's place is the vertical navigation because it's where the site-wide messages belong. The Top Bar will only be used for contextual tools/actions that belong to the content/forms on the page.
Now that the Navigation is in core can be addressed.