amenity filter and externally given poi file

[asu-trans-ai-lab]

the current function: net = og.getNetFromFile('asu.osm', POI=True)
might lead to many records.

We hope to have net = og.getNetFromFile('asu.osm', POI=True, amenity_type=("parking", "parking_space") to only extract specified type of amenity. similar to network_types=('auto', "bike", "walk")

In addition, if the users manually filter out the data the in poi.csv, then og.connectPOIWithNet(net) should be enhanced to read the externally given poi csv file, similar to node_file='node.csv',

i.e. og.connectPOIWithNet(net, poi_file = "poi.csv")

those functions are important to ev charging space planning and multimodal city planning.