Update StringHelper to avoid converting int's encoding to utf8

[REJack]

Hi together,

I recently hit an problem with the latest version (1.3.0) & with dev branch.
If I select an server by id and the serverId is 11+ it results in an convert error,

After some research I found out that using mb_convert_encoding on 11-19 result in some weird characters like ㄱ as 11 or ㄹ as 19 🤣

I assume that will fix #212.

[maxbrokman]

Also have encountered the same problem, especially with server group IDs getting converted into Japanese Kanji. We have a fork that implements the same fix and works. It might also be worth skipping the StringHelper entirely when the value is an integer or a Node->getId() as well?