Allow steps to fail with error message

Summary:
Add a method to add error messages into failed steps. This will be surfaced in the diagnostic screen, to help the user
troubleshoot.

Reviewed By: passy

Differential Revision: D9333322

fbshipit-source-id: 5f1e55c3d71b19292dbc428aaecfbd41e7a75125

xplat/Sonar/SonarStep.cpp

@@ -9,17 +9,22 @@
 #include "SonarState.h"
 
 void SonarStep::complete() {
-  isCompleted = true;
+  isLogged = true;
   state->success(name);
 }
 
+void SonarStep::fail(std::string message) {
+  isLogged = true;
+  state->failed(name, message);
+}
+
 SonarStep::SonarStep(std::string step, SonarState* s) {
   state = s;
   name = step;
 }
 
 SonarStep::~SonarStep() {
-  if (!isCompleted) {
+  if (!isLogged) {
     state->failed(name, "");
   }
 }