Move YGLogger into YGConfig and associate YGNodeRef with log events

Summary:
Moves the `YGLogger` into `YGConfig` and pass the `YGNodeRef` into the logger to be able to associate the log messages and assertions with the specific node.

Tackles facebook/yoga#530 and facebook/yoga#446
Closes https://github.com/facebook/yoga/pull/531

Reviewed By: astreet

Differential Revision: D4970149

Pulled By: emilsjolander

fbshipit-source-id: b7fcdaa273143ea2fa35861620b2e4d79f04f0af

enums.py

@@ -90,6 +90,7 @@ ENUMS = {
         'Info',
         'Debug',
         'Verbose',
+        'Fatal',
     ],
     'ExperimentalFeature': [
         # Mimic web flex-basis behavior.