Add multiple feature types to a single request

[eti7075]

Currently, overturemaps-py commands only allow for one feature type to be downloaded per command. It would be great to be able to download more than one type per request. For example, using the current options, a new command could look like overturemaps download --bbox 3, 51, 3, 51 -f geojson --type infrastructure,land

[Bonkles]

@eti7075 can you link the branch where you began creating the explorer experience for directing users to the python downloader here? Screenshots etc. useful to illustrate what we're after.

[eti7075]

Do you mean the callout from the download button or the 'command generator' that would provide the user with each command needed to download the visible view?