Add unaudited exported flag to exposed runtime receivers

Android T allows apps to declare a runtime receiver as not exported
by invoking registerReceiver with a new RECEIVER_NOT_EXPORTED flag;
receivers registered with this flag will only receive broadcasts from
the platform and the app itself. However to ensure developers can
properly protect their receivers, all apps targeting U or later
registering a receiver for non-system broadcasts must specify either
the exported or not exported flag when invoking #registerReceiver;
if one of these flags is not provided, the platform will throw a
SecurityException. This commit updates all the exposed receivers
with a new RECEIVER_EXPORTED_UNAUDITED flag to maintain the existing
behavior of exporting the receiver while also flagging the receiver
for audit before the U release.

Bug: 234659204
Test: Build
Change-Id: I0dd2c65d7e1c4c0e27a67e55b5b134ee2afad5b7

core/tests/bandwidthtests/src/com/android/bandwidthtest/util/ConnectionUtil.java

@@ -99,7 +99,8 @@ public class ConnectionUtil {
         // Register a download receiver for ACTION_DOWNLOAD_COMPLETE
         mDownloadReceiver = new DownloadReceiver();
         mContext.registerReceiver(mDownloadReceiver,
-                new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
+                new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE),
+                Context.RECEIVER_EXPORTED_UNAUDITED);
 
         // Register a wifi receiver
         mWifiReceiver = new WifiReceiver();