google-ipmi-sys: Refactor to use new version of OEM IPMI Handler

Using the new version of ipmi handler provide a higher level wrapper
over the same functionalities. It helps us parse the input and output to
have more control of the input/output we see.

The input and output will be
`std::uint8_t, std::optional<std::vector<uint8_t>>`.

This represents `subcommand` and any input data.

Changes to note,
- all subcommand in the request/response struct are removed. It will be
  managed by the wrapper directly.
    - Unit tests checking for input with only the subcommand are
      removed.
- Move all reply struct to header files to be accessible in unit test.

Tested:
All IPMI OEM command still works the same as before this change.

Change-Id: I4230ab84a497a867248fe82224e32cc69b314b64
Signed-off-by: Willy Tu <wltu@google.com>
diff --git a/ipmi.hpp b/ipmi.hpp
index 62754c2..ef8c627 100644
--- a/ipmi.hpp
+++ b/ipmi.hpp
@@ -18,15 +18,19 @@
 
 #include <ipmid/api.h>
 
+#include <ipmid/api-types.hpp>
+#include <ipmid/message.hpp>
+#include <optional>
+#include <vector>
+
 namespace google
 {
 namespace ipmi
 {
 
 // Handle the google-ipmi-sys IPMI OEM commands.
-ipmi_ret_t handleSysCommand(HandlerInterface* handler, ipmi_cmd_t cmd,
-                            const uint8_t* reqBuf, uint8_t* replyCmdBuf,
-                            size_t* dataLen);
+Resp handleSysCommand(HandlerInterface* handler, ::ipmi::Context::ptr ctx,
+                      uint8_t cmd, const std::vector<uint8_t>& data);
 
 } // namespace ipmi
 } // namespace google