Reshape org user management

Following the shaping of the new version of Account Management in Connect Dashboard, the way users are managed should look like this:

https://www.figma.com/proto/y2uw7SQPzoTmWwlhFldx2B/Nexio-User-Management?node-id=467%3A353322&scaling=min-zoom&page-id=124%3A4116&starting-point-node-id=439%3A347282&show-proto-sidebar=1

Changes to me made on current page:

• Separate the users list in a new tab called "Users"
• Reshape the polymer element with new design
• Add a short list (2-3 max) of users group on a user row: include only groups that are related to the current org
  • Show user details page when user row is clicked: will display all the current org related groups the user is member of + some other details (user creation date ? number of organizations ?) No further detail - 'Edit', 'delete' need to be added, reuse current icons // Should we create a user page
    User detail page yes, lists groups
• Add an icon to edit user on each row ? yes and delete 

• Add an icon to manage user groups on each row ? groups page

The new page will only be available by URL for now, we keep the current Account Mngt page available via Menu