Adding the Mattapan trolley

[devinmatte]

Motivation

Adds the Mattapan Trolley to the dashboard

We already have the data for it and the performance API supports it

Need to make sure some of the stops are correct, whoever reviews please sanity check stations.json stop maps

Changes

Adds the Mattapan Trolley to the dashboard using Subway presets and a few disabled pages

Testing Instructions

Test on beta, paying attention to weirdness

[rudiejd]

all of the frontend stuff lgtm in the beta, I'll wait to approve until we have the data sorted though

[devinmatte]

Data is missing for from=70276 and to=70274. All other stop pairs have valid data.

May need to contact the MBTA to figure out why, or dig into LAMP data to figure out if there's a stop id that doesn't exist in the v3 api

[devinmatte]

Missing data is a known issue. Doesn't block releasing, but does require a notice and maybe to disable selecting it in the UI

[devinmatte]

Requires transitmatters/data-ingestion#117 now to merge

[skaplan-dev]

Did a quick glance at the gtfs for the stop ids but it looks good 👍