Implement the APIs for gRPC calls in client/server

Implement the APIs defined in the RdcStandaloneHandler to make gRPC call to daemon

Implement the APIs defined in the RdcAPIServiceImpl to handle the gRPC calls in daemon

Add two APIs to get all GPU groups and field groups: rdc_group_get_all_ids()
and rdc_group_field_all_ids()
Those two APIs are required by the rdci group and fieldgroup
sub-modules.

Change-Id: I066091423146dea180c16af212688ed43dc44611

example/job_stats_example.cc

@@ -104,11 +104,11 @@ int main(int, char **) {
     }
 
     // For standalone mode, the daemon will update and cache the samples
-    // In manual mode, we must call rdc_update_all_fields periodically to
+    // In manual mode, we must call rdc_field_update_all periodically to
     // take samples.
     if (!standalone) {  // embedded manual mode
         for (int i=5; i > 0 ; i--) {  // As an example, we will take 5 samples
-            result = rdc_update_all_fields(rdc_handle, 0);
+            result = rdc_field_update_all(rdc_handle, 0);
         if (result != RDC_ST_OK) {
             std::cout << "Error update all fields. Return: "
                 << rdc_status_string(result);