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/packages/Shell/AndroidManifest.xml b/packages/Shell/AndroidManifest.xml
index 8cfc2a6..bff2c84 100644
--- a/packages/Shell/AndroidManifest.xml
+++ b/packages/Shell/AndroidManifest.xml
@@ -82,6 +82,7 @@
     <uses-permission android:name="android.permission.CLEAR_APP_CACHE" />
     <uses-permission android:name="android.permission.DELETE_CACHE_FILES" />
     <uses-permission android:name="android.permission.DELETE_PACKAGES" />
+    <uses-permission android:name="android.permission.MANAGE_ROLLBACKS" />
     <uses-permission android:name="android.permission.ACCESS_SURFACE_FLINGER" />
     <uses-permission android:name="android.permission.READ_FRAME_BUFFER" />
     <uses-permission android:name="android.permission.DEVICE_POWER" />