[Feature Request]: Ability to pass the default experiment as module argument to be selected in the encoding panel

### Feature description

The MAE experiment UI is created using the `experimentSpecInput()` which could be extended to also take in `exp_name` along with the `mae_name` so that the select input is populated with the default experiment that the module caller wants.

The [motivation for this request](https://github.com/insightsengineering/teal.slice/issues/526#issuecomment-1916496507) is that the **RNA-seq** app in the `teal.gallery` only has data in the experiment `hd2` so when the Forestplot module is initiated the choices for the experiments is pre-populated with `hd1`.

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