[denali] Add a stub client for denali

sys/denali/include/denali/denali_client.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <mammoth/channel.h>
+#include <mammoth/memory_region.h>
+
+class DenaliClient {
+ public:
+  DenaliClient(const Channel& channel) : channel_(channel) {}
+
+  MappedMemoryRegion ReadSectors(uint64_t device_id, uint64_t lba,
+                                 uint64_t num_sectors);
+
+ private:
+  Channel channel_;
+};