Vpn settings per vpn

This CL adds a setting for each VPN
- When no_config_vpn user restriction is applied, user can't change anything in the page
- Launch the subsetting activity in the corresponding user to unlock keystore and force work challenge
- Show dialog when user replace always-on-VPN package
- When forget VPN, unset always-on-vpn

TODO: show per-VPN status in VPN list

Change-Id: Ica360ea44117db6a4ecfaed1eec6c188189c246c

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

@@ -355,8 +355,7 @@ public class VpnSettings extends RestrictedSettingsFragment implements
             } else if (tag instanceof AppPreference) {
                 AppPreference pref = (AppPreference) tag;
                 boolean connected = (pref.getState() == AppPreference.STATE_CONNECTED);
-                AppDialogFragment.show(VpnSettings.this, pref.getPackageInfo(), pref.getLabel(),
-                        true /* editing */, connected);
+                AppManagementFragment.show(getPrefContext(), pref);
             }
         }
     };