[Conformal EEG] TUEV Dataset and Task (#752)

* Add TUEV dataset configuration and initial implementation

* Add EEGEventsTUEV task

* Add TUEV EEG quickstart notebook for dataset loading and model training

* Refactor TUEV dataset configuration by removing train_index and eval_index

* Add unit tests for TUEV dataset and EEGEventsTUEV task functionality

* Remove unused EEG processing functions from TUEV task implementation

* Remove unused EEG functions from TUEV task imports

* Add examples for TUEVDataset and EEGEventsTUEV in docstring

Author: Razin93937