Add human supervision to ChemGraph

[tdpham2]

Problem

Currently, ChemGraph only handles 1 human input prompt (additional prompt via --resume tag to continue conversation). Need to add extra capability to ChemGraph to ask human question and use human's feedback to improve (optionally).

Proposed solution

• Add ask_human tool for agent.
• Add human_supervised parameter for flexibility.
• Update single_agent and multi_agent graph

Checks
Make sure the solution works in:

• CLI
• Jupyter-notebook
• UI (streamlit)

[tdpham2]

Added in #119. Will close once merged to main