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/eth.hpp b/eth.hpp
index 046ac77..0fe8d4e 100644
--- a/eth.hpp
+++ b/eth.hpp
@@ -18,6 +18,9 @@
 
 #include <ipmid/api.h>
 
+#include <ipmid/api-types.hpp>
+#include <vector>
+
 namespace google
 {
 namespace ipmi
@@ -28,7 +31,6 @@
 // ncis connection.
 struct EthDeviceReply
 {
-    uint8_t subcommand;
     uint8_t channel;
     // ifNameLength doesn't include the null-terminator.
     uint8_t ifNameLength;
@@ -37,8 +39,8 @@
 // Handle the eth query command.
 // Sys can query the ifName and IPMI channel of the BMC's NCSI ethernet
 // device.
-ipmi_ret_t getEthDevice(const uint8_t* reqBuf, uint8_t* replyBuf,
-                        size_t* dataLen, const HandlerInterface* handler);
+Resp getEthDevice(const std::vector<std::uint8_t>& data,
+                  const HandlerInterface* handler);
 
 } // namespace ipmi
 } // namespace google