FR: Report artifacts from Optuna studies via MlFlow

**Is your feature request related to a problem? Please describe.**
Currently results of the Optuna studies can only be accessed via Optuna-Dashboard and are therefore hard to extract.

**Describe the solution you'd like**
Report the results as plotly figures via the available api [here](https://optuna.readthedocs.io/en/v2.0.0/reference/visualization.html) as mlflow artifacts.

**Describe alternatives you've considered**
Store data directly via MlFlow but that would cause unnecessary redundancy. If we would need to access the data directly the effort justifies making some short queries to the Optuna SQL database directly.

**Additional context**
N/A

Locate the repository's MLflow reporting entry point and review the linked Optuna visualization API. Determine which Plotly figures should be stored as MLflow artifacts, then verify completion by retrieving those artifacts from an MLflow run without duplicating the underlying study data.

Written by the indexing model from the issue text.