Create a EcoPoint reward estimation functionality given a mission

[hoanghm]

• [ ] Prepare a range of examples of how much EcoPoint should be awarded based on task difficulty.
• [ ] Create a function to estimate EcoPoint awarded given a mission.
• [ ] Add EcoPoint estimation as a component in the chain of prompts when generating missions: user info --> env problems --> env events --> mission --> CO2 estimation --> EcoPoint estimation