[#189] client: Make PrmInit fields public for client

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

client/object_put_raw.go

@@ -28,7 +28,7 @@ func (c *Client) objectPutInitRaw(ctx context.Context, prm PrmObjectPutInit) (*o
 		return nil, fmt.Errorf("open stream: %w", err)
 	}
 
-	w.key = &c.prm.key
+	w.key = &c.prm.Key
 	if prm.Key != nil {
 		w.key = prm.Key
 	}