Replace GTFS Components language to GTFS features

[emmambd]

We're adding #1652 to the upcoming release so it's easier for us to ingest the validation metadata as a part of the next stage of the Mobility Database API . This is a breaking change to the JSON report, so now is a good time to also make a breaking modification to the "GTFS Components" label and replace it with "GTFS Features" so it's harmonized across the Mobility Database and gtfs.org.

Tasks

• JSON and HTML report modifications to the GTFS Schedule validator report.
• Include both components and features label in the next release and provide "deprecated" notation for the components label.