Add token count to the Chat history table

[vmesel]

No description provided.

[lgabs]

I think it's possible to monitor this manually, but langsmith already helps with that in a very elegant way in terms of observability, including latency and other metrics. This is a very good way of monitoring the application for dialog developers. Maybe this issue would be about logging this kind of metric in the history table for other purposes?

Here is an example:

[vmesel]

@lgabs I didn't know about this feature on langsmith, @avelino told me you were using it and I got really excited to know more about it.

My original plan was just to look at costs on tokens and how we are spending them through messages.