Make setAirplaneMode @SystemApi for SetupWizard.

Expose ConnectivityManager#setAirplaneMode and the
NETWORK_SETUP_WIZARD permission so that SetupWizard can call
setAirplaneMode.

Delete setAirplaneMode from the greylist because the permissions
checks on it, since at least 2013, have been for a privileged
permission (CONNECTIVITY_INTERNAL) that normal apps don't have.

Test: m
Bug: 115302596
Change-Id: I28f24d32c4b4b386407e9e0e3514ea9f8854f4a8
diff --git a/core/java/android/net/ConnectivityManager.java b/core/java/android/net/ConnectivityManager.java
index 8333b81..ee38612 100644
--- a/core/java/android/net/ConnectivityManager.java
+++ b/core/java/android/net/ConnectivityManager.java
@@ -2728,7 +2728,7 @@
      * @hide
      */
     @RequiresPermission(android.Manifest.permission.CONNECTIVITY_INTERNAL)
-    @UnsupportedAppUsage
+    @SystemApi
     public void setAirplaneMode(boolean enable) {
         try {
             mService.setAirplaneMode(enable);