Since I was going to make yet another button for the ElasticSearch test
config button, I refactored all of them to use a single common component
and tidied that component up and gave it some unit tests.
* PLT-2713 Added ability for admins to list users not in any team
* Updated style of unit test
* Split SearchableUserList to give better control over its properties
* Added users without any teams to the user store
* Added ManageUsers page
* Renamed ManageUsers to SystemUsers
* Added ability to search by user id in SystemUsers page
* Added SystemUsersDropdown
* Removed unnecessary injectIntl
* Created TeamUtils
* Reduced scope of system console heading CSS
* Added team filter to TeamAnalytics page
* Updated admin console sidebar
* Removed unnecessary TODO
* Removed unused reference to deleted modal
* Fixed system console sidebar not scrolling on first load
* Fixed TeamAnalytics page not rendering on first load
* Fixed chart.js throwing an error when switching between teams
* Changed TeamAnalytics header to show the team's display name
* Fixed appearance of TeamAnalytics and SystemUsers on small screen widths
* Fixed placement of 'No users found' message
* Fixed teams not appearing in SystemUsers on first load
* Updated user count text for SystemUsers
* Changed search by id fallback to trigger less often
* Fixed SystemUsers list items not updating when searching
* Fixed localization strings for SystemUsers page
* Reorganized system console
* Fixed the names of some components
* Fixed timestamp for BrandImageSetting
* Fixed merge issues
* Updated push notification settings to match master branch
* Removed top level setting pages and moved enable Gitlab/LDAP settings onto their respective pages
* Re-added restrictDirectMessage setting to system console
* Re-added email connection test and fixed some margins
* Fixed ESLint errors
* Renamed Authentication > Onboarding to Authentication > Email in the system console
* Renamed Customization > Whitelabeling to Customization > Custom Branding in System Console
* Re-added EnableOpenServer to system console
