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/EnterprisePrivacyFeatureProviderImpl.java

@@ -96,4 +96,9 @@ public class EnterprisePrivacyFeatureProviderImpl implements EnterprisePrivacyFe
         return managedProfileUserId != -1 &&
                 VpnUtils.isAlwaysOnVpnSet(mCm, managedProfileUserId);
     }
+
+    @Override
+    public boolean isGlobalHttpProxySet() {
+        return mCm.getGlobalProxy() != null;
+    }
 }