Improve history panel in streamlit app

[jbloomAus]

• [x] I've worked out how to convert one hot encoded obs back into obs, so make use of that to show the history from the agent pov (optionally)
• [x] I think the action listed seems off/janky. worth a look
• [x] Rather than use a streamlit slider, use a plotly slider so this doesn't trigger refreshes.

[jbloomAus]

Could still use some improvements, like labelling the tokens. but good enough for now.