Limit bypass staged installer API to system and shell only

Bug: 148664742
Test: manually check access the api inproperly throws
Change-Id: I568b9df87d30c8da6dd85f0310bf7af1d60b4ea3

services/core/java/com/android/server/pm/PackageInstallerService.java

@@ -979,6 +979,9 @@ public class PackageInstallerService extends IPackageInstaller.Stub implements
 
     @Override
     public void bypassNextStagedInstallerCheck(boolean value) {
+        if (!isCalledBySystemOrShell(Binder.getCallingUid())) {
+            throw new SecurityException("Caller not allowed to bypass staged installer check");
+        }
         mBypassNextStagedInstallerCheck = value;
     }