ImGui: increase base64 key buf size

Make buffer size as large as that of the engine itself (used to represent the string in class CNetKey).

src/gameui/IBrowser.h

@@ -49,7 +49,7 @@ private:
     bool m_queryGlobalBanList;
     char m_serverTokenTextBuf[128];
     char m_serverAddressTextBuf[128];
-    char m_serverNetKeyTextBuf[30];
+    char m_serverNetKeyTextBuf[45];
 
     ID3D11ShaderResourceView* m_lockedIconShaderResource;
     MODULERESOURCE m_lockedIconDataResource;