packaging: setup: remote_engine: manual_files: Read as binary

Make remote_engine_manual_files.py match the behavior of
remote_engine_root_ssh.py, and so make 'copy_from_engine' return a bytes
object, not str.

This should fix the bug that [1] was supposed to fix, but [1] only fixed
it for the 'manual files' mode and broke paramiko/ssh.

[1]
oVirt/ovirt-dwh@885d65f

Change-Id: I32cd8aff5e851fb053b2cd5b8237455ce2230a35
Signed-off-by: Yedidyah Bar David <didi@redhat.com>

packaging/setup/plugins/ovirt-engine-common/base/remote_engine/remote_engine_manual_files.py

@@ -83,7 +83,7 @@ def copy_from_engine(self, file_name, dialog_name=None):
                 ),
                 prompt=True,
             )
-            with open(resfilename) as f:
+            with open(resfilename, 'rb') as f:
                 res = f.read()
             return res