Add lockdownEnabled parameter to always-on VPN API

Allows callers to opt-out of blockading network traffic during boot and
on VPN app failure.

Bug: 26694104
Change-Id: Ic2c25b79d8a17917025eb37be7de929fe156e2a3

src/com/android/settings/vpn2/AppManagementFragment.java

@@ -176,7 +176,8 @@ public class AppManagementFragment extends SettingsPreferenceFragment
         if (mUserId == UserHandle.USER_SYSTEM) {
             VpnUtils.clearLockdownVpn(getContext());
         }
-        mConnectivityManager.setAlwaysOnVpnPackageForUser(mUserId, isEnabled ? mPackageName : null);
+        mConnectivityManager.setAlwaysOnVpnPackageForUser(mUserId, isEnabled ? mPackageName : null,
+                /* lockdownEnabled */ false);
         if (isEnabled && !isVpnAlwaysOn()) {
             CannotConnectFragment.show(this, mVpnLabel);
         }