The Diagnostic API interface

The API interface defines how the caller will use the API. An
example also shows how the API can be used.
It also defines the RdcDiagnostic module which can load the
library dynamically and then dispatch diagnostic test to run.

Change-Id: I1e041aab86f7e19338860f5ba65262977f4ea9cb

include/rdc_lib/impl/RdcEmbeddedHandler.h

@@ -86,6 +86,11 @@ class RdcEmbeddedHandler: public RdcHandler {
         uint64_t *next_since_time_stamp, rdc_field_value* value) override;
     rdc_status_t rdc_field_unwatch(rdc_gpu_group_t group_id,
         rdc_field_grp_t field_group_id) override;
+    // Diagnostic API
+    rdc_status_t rdc_diagnostic_run(
+        rdc_gpu_group_t group_id,
+        rdc_diag_level_t level,
+        rdc_diag_response_t* response) override;
     // Control API
     rdc_status_t rdc_field_update_all(uint32_t wait_for_update) override;