Patch on world logging

[jxmsML]

Patch on world logging

• filter by message.is_padding() when writing episodes to self._current_episodes.
• modify the test tests/test_eval_model.py on test_save_report to verify the no dummy world logs are stored (those with batch_padding True)

before this patch:
the world logs saved will contain the following dummy episode:

{"dialog": [[{"batch_padding": true, "episode_done": true, "id": "bot_adversarial_dialogue:HumanSafetyEvaluation.persona_False_flatten_False"}, {"id": "TransformerGenerator", "episode_done": false}]], "context": [], "metadata_path": "random/world_logs.metadata"}

After this patch, no such padding examples will be saved to the world logs

Testing steps

Other information

[stephenroller]

We might want to cast it as a message in case it happens to be a dict