Support transit land in the GTFS query tool

[kuanb]

This is currently en route via this branch: kuanb-gtfs-feeds-query-util.

Should allow the same functionality as curr exists w/ GTFS Data Exch.

[knaaptime]

i've got a little feeds_from_bbox function here that i'd be happy to contribute if its of interest. Afaict it accomplishes the spirit of this issue, though obviously works a bit differently than the current downloader

[sablanchard]

thanks @knaaptime yes we would be happy to accept this contribution! This was on our roadmap to tackle at some point but we have not gotten to it. Ideally it would function identical to the existing GTFS Data Exch functions (with of course support for the bbox query) however we can take a look at doing modifications afterwards to get it to match the functions there if you dont have time to put together something now like that. Feel free to make a PR when you can.