[#770] pkg/morph/container: Add `Morph()` method

Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>

pkg/morph/client/container/wrapper/wrapper.go

@@ -31,6 +31,11 @@ func defaultOpts() *opts {
 	return new(opts)
 }
 
+// Morph returns raw morph client.
+func (w Wrapper) Morph() *client.Client {
+	return w.client.Morph()
+}
+
 // TryNotary returns option to enable
 // notary invocation tries.
 func TryNotary() Option {