Using a separate IOClient for asset handler and reader when serving with the DDC Library Bundle module system (#2832)

This aligns its behavior with that of the AMD module system.

I suspect DDC Library Bundle specific flakes on CI may have been caused by this overloaded shared client. Example:
```
  getObject: (-32603) Unexpected DWDS error for getObject: ClientException with SocketException: Connection reset by peer (OS Error: Connection reset by peer, errno = 104), address = localhost, port = 43454, uri=http://localhost:41739/web/main.ddc.js.map
```