As a system user I want to compare the forecast and in situ data for a single city (Part 2)

Description

This page will be used to compare forecast/in situ for a single city.

This ticket depends on #60 being completed so has scope only for the displaying the in situ data in the UI for a single city

Under route /city/{city_name}, the UI will show the a line chart showing in situ data for a city (next to forecast)
- Use API /air-pollutant/measurements to fetch forecast data for city (already done in previous ticket)
- Data here should be aggregated on the front end with AQI levels being calculated. This should be done so that it ties into forecast_valid_time from the forecast (measurements within -/+1.5 hours after each forecast_valid_time is aggregated and averaged together)
- The measurement data should tie in with site selection When sites are selected/deselected, measurements are filtered out accordingly