Admin panel site: users

[Shirajuki]

Part of issue #9 and includes the users part of the admin panel site.

This includes:

• List view over all the users UI #44
• Fetch users from db and show in table #48
• filtering and sorting on the list view (w/wo membership, isAdmin, ...)
• ability to click on, open and edit specific users #51
• edit user form UI #50
  • should be able to see, connect and disconnect the different relations with the users as well
    • membership
    • events
  • I should be able to add a new user
  • add consent check box for social media