Remove problematic bigint encoding

This MR removes DHKey model and its problematic bigint encoding. This is a workaround until a better solution is developed. For now, the GroupMember model will be missing dhKey property.

Sources/XXClient/Helpers/ConvertJsonNumberToString.swift

@@ -17,3 +17,21 @@ func convertJsonNumberToString(
   }
   return output
 }
+
+func convertJsonNumberToString(
+  in input: Data,
+  minNumberLength: Int
+) -> Data {
+  guard var string = String(data: input, encoding: .utf8) else {
+    return input
+  }
+  string = string.replacingOccurrences(
+    of: #":( *)([0-9]{\#(minNumberLength),})( *)(,*)"#,
+    with: #":$1"$2"$3$4"#,
+    options: [.regularExpression]
+  )
+  guard let output = string.data(using: .utf8) else {
+    return input
+  }
+  return output
+}