v1.0.0: Add Planet imagery metadata retrieval

[zcrennenLANL]

Line 1019 in prepTrainInputs/main1Utils.py describes the function to retrieve metadata from Vantor (fk Maxar/Worldview) imagery. As this was initially used for strictly Vantor imagery, hardcoding this retrieval maked sense. To add support for Planet imagery, this should use an if/else or try/except block to sort between imagery source. Fill in appropriate code to extract metadata from Planet's metadata descriptions. For ease of user experience this ideally classifies imagery source automatically, perhaps with a try/except block, however, an addition of an "imagerySource" variable to the .env file may be acceptable.

[mia-mitchell]

Sounds good. Working on getting access to Planet Imagery. I will add it to both V0.0.0 and V1.0.0. Still, in the paper, trying to discern if there are areas in V0.0.0 that could be streamlined without losing its ability to hand-hold users.