Make RollbackManager @SystemApi.

Require callers hold a new MANAGE_ROLLBACKS permission to interact with
the RollbackManager.

Bug: 112431924
Test: atest RollbackTest, with new test for permissions added,
      and with selinux in permissive mode.
Test: atest CtsPermission2TestCases:PermissionPolicyTest
Change-Id: I73f4f3457d85be580670cd69c89066d2cc348186
diff --git a/core/res/AndroidManifest.xml b/core/res/AndroidManifest.xml
index b16c16d..be37ca9 100644
--- a/core/res/AndroidManifest.xml
+++ b/core/res/AndroidManifest.xml
@@ -3854,6 +3854,10 @@
     <permission android:name="android.permission.PACKAGE_ROLLBACK_AGENT"
         android:protectionLevel="signature" />
 
+    <!-- @SystemApi @hide Allows managing apk level rollbacks. -->
+    <permission android:name="android.permission.MANAGE_ROLLBACKS"
+        android:protectionLevel="signature|installer" />
+
     <!-- @SystemApi @hide Allows an application to mark other applications as harmful -->
     <permission android:name="android.permission.SET_HARMFUL_APP_WARNINGS"
         android:protectionLevel="signature|verifier" />