Apply Nullsafe FIXMEs for xplat/js/react-native-github/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java (#50059)

Summary:
Pull Request resolved: #50059

Note this diff is only adding FIXMEs that will be removed in the next diff. This diff exists to make the next diff easily reviewable

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D71126395

fbshipit-source-id: fb42b12dae542bde6e0e9e58baeaab054ed8c49e

Author: GijsWeterings

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java

@@ -208,6 +208,7 @@ protected Void doInBackground(Void... params) {
 
         mInspectorPackagerConnection =
             new CxxInspectorPackagerConnection(
+                // NULLSAFE_FIXME[Parameter Not Nullable]
                 getInspectorDeviceUrl(), metadata.get("deviceName"), mPackageName);
         mInspectorPackagerConnection.connect();
         return null;
@@ -457,6 +458,7 @@ public String getSourceUrl(String mainModuleName) {
       }
 
       try (Sink output = Okio.sink(outputFile)) {
+        // NULLSAFE_FIXME[Nullable Dereference]
         Okio.buffer(response.body().source()).readAll(output);
       }