Add idb check to doctor

Summary:
Adds a check for idb to flipper-doctor.

This depends on the flipper settings, to know where to look for idb, so I've made it so you can pass settings into the doctor when running it. When run from the command line, you don't get the settings. This is because settings loading currently depends on redux so I haven't extracted it into its own package.

Not that this will notify ALL open source iOS users with a doctor warning because they don't have idb installed. The error message says you can disable it in settings, which will silence this warning.

CHANGELOG: The open source version now works with physical iOS devices.

Reviewed By: passy

Differential Revision: D21883086

fbshipit-source-id: f28c43487e88a6c07ef3cc3da2764026726c9f18

desktop/app/src/dispatcher/iOSDevice.tsx

@@ -258,7 +258,9 @@ export default (store: Store, logger: Logger) => {
   isXcodeDetected().then((isDetected) => {
     store.dispatch(setXcodeDetected(isDetected));
     if (isDetected) {
-      startDevicePortForwarders();
+      if (store.getState().settingsState.enablePhysicalIOS) {
+        startDevicePortForwarders();
+      }
       return queryDevicesForever(store, logger);
     }
   });