Use Hydra for config management of feature decoding code

[ShuntaroAoki]

Working branch: https://github.com/KamitaniLab/brain-decoding-cookbook-public/tree/feature-decoding

• featdec_fastl2lir_train.py
• featdec_fastl2lir_predict.py
• featdec_eval.py
• featdec_sklearnRidge_train.py
• featdec_predict.py
• featdec_cls_linsvm_train.py
• featdec_cls_predict.py