Add typings to config.

[renezurbruegg]

• [x] Make Config TypeDict -> check missing attributes
  • [x] General (version, work_dir, experiment_name)
  • [x] Hyperparameters (seed, samples_per_gpu, ...)
  • [x] Model
  • [x] Loss
  • [x] Optimizer
  • [x] Data connector
  • [x] Callbacks