utils: introduce EngineSSHClient wrapper

EngineSSHClient enables the use of SSHClient it defaults of engine, it
will also enable us to override methods such as connect at a single
place.

Change-Id: I1993ac7e01963135aa8f53ce481b308b6531ecd3
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>