PLT-2257 Reorganized System Console (#3003)

* 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

webapp/stores/admin_store.jsx

@@ -22,7 +22,7 @@ class AdminStoreClass extends EventEmitter {
         this.logs = null;
         this.audits = null;
         this.config = null;
-        this.teams = null;
+        this.teams = {};
         this.complianceReports = null;
     }
 
@@ -126,6 +126,10 @@ class AdminStoreClass extends EventEmitter {
         this.teams = teams;
     }
 
+    getTeam(id) {
+        return this.teams[id];
+    }
+
     getSelectedTeams() {
         const result = BrowserStore.getItem('seleted_teams');
         if (!result) {