Add global HTTP proxy to Privacy Settings page

This CL allows the user to see on the Enterprise Privacy Settings
page whether the admin set a global HTTP proxy.

Test: make RunSettingsRoboTests
Bug: 32692748

Change-Id: I3c7c46f806f39c90425fd8e098a749f3cc1e9278

src/com/android/settings/enterprise/EnterprisePrivacySettings.java

@@ -63,6 +63,7 @@ public class EnterprisePrivacySettings extends DashboardFragment {
         controllers.add(new SecurityLogsPreferenceController(context));
         controllers.add(new AlwaysOnVpnPrimaryUserPreferenceController(context));
         controllers.add(new AlwaysOnVpnManagedProfilePreferenceController(context));
+        controllers.add(new GlobalHttpProxyPreferenceController(context));
         return controllers;
     }