Make the interops and http helpers internal

Author: AustinBenoit

firebaseai/src/LiveGenerativeModel.cs

@@ -22,6 +22,7 @@
 using System.Threading;
 using System.Threading.Tasks;
 using Firebase.AI.Internal;
+using Firebase.Internal;
 using Google.MiniJSON;
 
 namespace Firebase.AI

functions/src/FunctionsException.cs

@@ -46,4 +46,4 @@ internal FunctionsException(FirebaseException e): base(e.Message)
       ErrorCode = (FunctionsErrorCode) e.ErrorCode;
     }
   }
-}`
+}

functions/src/HttpsCallableReference.cs

@@ -22,6 +22,7 @@
 using System.Net.Http;
 using System.Net;
 using Firebase.Functions.Internal;
+using Firebase.Internal;
 using System.Text;
 using System.Runtime.InteropServices.WindowsRuntime;