Add isHeadless attribute to scribe messages

Summary:
So we can distinguish between humans and the machines.

We can redirect the traffic to different tables based on this attribute if necessary.

Reviewed By: danielbuechele

Differential Revision: D14025004

fbshipit-source-id: c3a24b5f8a30f24445eaee67843b78ddabfc9d51

src/fb-stubs/Logger.js

@@ -12,8 +12,12 @@ import ScribeLogger from './ScribeLogger';
 
 var instance: ?LogManager = null;
 
+type Args = {
+  isHeadless?: boolean,
+};
+
 export default class LogManager {
-  constructor(store: Store) {
+  constructor(store: Store, args?: Args) {
     this.scribeLogger = new ScribeLogger(this);
   }
 

src/reducers/index.js

@@ -53,7 +53,6 @@ export type State = {|
   plugins: PluginsState,
 |};
 
-// $FlowFixMe introduced when removing $Subtype/$Supertype
 export type Store = ReduxStore<State, Actions>;
 
 export default combineReducers<_, Actions>({