Create a base flask app with swagger/openapi enabled

[jyucsiro]

Create a base flask app to wrap functionality from https://github.com/GeoscienceAustralia/AusPIX_DGGS

Consider these lib for swagger/openapi bindings:

• https://github.com/python-restx/flask-restx
• https://github.com/flasgger/flasgger

Create a dockerfile extending python 3 base image. You can look at this for a template: https://github.com/CSIRO-enviro-informatics/geometry-data-service/blob/master/api/Dockerfile

[jyucsiro]

Another swagger or openAPI library to consider is connexion - https://github.com/zalando/connexion