Add simple query argument for human readable URL input

[SeanLeRoy]

See context in #432, but it seems like a simple addition to make it easy for users to construct a simple url linking to a dataset in BFF like so https://bff.allencell.org?url=https://my-data-server/my_file.csv. Of course this would need to assume things based on the URL provided or default to certain parameters, but it could be a nice simple addition.