Empty states for invited users

New users that are invited to existing groups and projects on GitLab don't get the context that empty states often offer. We should find a way to introduce the basic GitLab terms and features to these users so that they don't need to rely on finding this in our documentation or never truly learn about it.

Quick mockups of possible invited users empty states alternatives:

Mockup 1	Mockup 2

We would only show this to new GitLab users that recently joined via an invitation.