[Browser - Text-to-Cypher] Chat - improve experience

[shahar-biron]

Make the chat panel more professional:

1. Keep track of number of LLM tokens used in the session
2. Provide confidence level to each LLM response
3. When text2cypher has an error, show the error as part of the chat flow, and not as a temporary pop-up.
4. Add to the input box a checkbox, that the chat will only respond with the cypher query, and will skip executing on the graph and getting an LLM formatted response.