PyPortal NASA image viewer

[kevinjwalters]

There are two changes here:

1. Retrieving the NASA API key from secrets.py
2. Using a new feature in adafruit_pyportal to post-process JSON responses from NASA to convert any YouTube videos into a url for a still image.

The first requires documentation updates to:

• @jedgarpark's Adafruit Learn: PyPortal NASA Image of the Day Viewer on at least the Internet Connect! page.

The second must not be "released" until the

• change (Add new feature to allow changes/additions to the fetched and parsed JSON dict Adafruit_CircuitPython_PyPortal#38 & New optional json_transform arg to PyPortal constructor to post-process parsed JSON Adafruit_CircuitPython_PyPortal#39) to
• adafruit_pyportal is in the appropriate bundles.

The code to do the YouTube conversion might be better one day placed in a library of "converters".

[kevinjwalters]

https://github.com/adafruit/Adafruit_CircuitPython_PyPortal/tree/3.1.3 is latest at the moment and does not have the json_transform enhancement.