Proposal: Add elevator/escalator real-time status - extend `EntitySelector` to select pathways instead of only nodes

Hey! 👋

Are there any plans, documents, or issues to extend GTFS RT with elevator/escalator service disruptions already? Sozialhelden e.V., an NGO from Berlin, Germany, have covered a lot of German elevator status information in APIs but it would be much better if you could mark an elevator as broken via GTFS pathways.txt and a GTFS RT `EntitySelector`. This would allow providers to mark a pathway, instead of just stops, as unusable.

Here are some UX mockups how this could look to an end user:

To me it seems almost all infrastructure is ready for this.

I could try to provide a feed for the Verkehrsverbund Berlin Brandenburg (VBB) beta `pathways.txt` data set – there is real-time info for around 600 facilities. Any objections, feedback, or ideas? :)