Adding Yaml, Remove args

[ComTDK]

This PR is to:

• Add yaml file
• Remove args
• Using yaml to assign model config
• Add Validation step to training loop:
  • Run Validation on the next 10% of the total snapshots
  • Store the best model --> There is self.best_validation_model_auc to compare
• Resolve some comments:
  1. Return both encoder and decoder after self.train_models()
  2. Sample old nodes in the training loop
• Add gpu memory alloc

args to yaml:

• args.embedding --> yaml["encoder_model"]["addOnFeature"]
• args.embeddingType --> yaml["encoder_model"]["nodeEmbeddingType"]
• args.mlpEncoding --> yaml["decoder_model"]["encode_links"]