Add dummy backend data fetching

[haaspt]

Overview

This PR replaces the placeholder weather forecast data in the frontend with actual data fetching from the backend.

To accomplish this I added a /forecast/ endpoint to the backend. Currently it just randomly generates a list of conditions and temperatures regardless of what location is queried.

The frontend static data has been replaced with an async fetch call in WeatherForecast.js. This also involved adding additional states to store the data and the loading status.

How to Test

• Spin up the docker containers
• Navigate to localhost:8000/docs and test out the new endpoint
• Navigate to localhost:3000 and observe how weather data is dynamically populated
• [Optional] Kill only the backend service and observe how the weather data never populates and the widgets are stuck in a "loading" state.

[haaspt]

The frontend is technically located at a different origin so we have to enable CORS so the requests will be allowed. More here.

[haaspt]

useEffect accepts a final argument that describes its dependencies. Anytime a dependency is updated the effect will run again. In this case we just need this to run once when the container mounts so we shouldn't have any dependencies. However, since we're using locationData in our API call we need to include it as a dependency (even if we don't expect it to change inside the container)