Show running elevators/escalators

[devinmatte]

It would be great if we can show how actually accessible the stations in the T are somewhere in the UI of the dashboard

Blue Line
Escalators 4/10 in service
Elevators 9/10 in service

https://www.mbta.com/alerts/access should show us elevators/escalators closures, and we can use that to create aggregate metrics of availability