Integrate Instagram importer

Seems like there are two ways to go about this and I'm resistant to chose just one when we can probably have both:

https://github.com/Automattic/data-liberation-agent/pull/18
https://github.com/MaggieCabrera/instagram-importer

Importing the data requires deciding how to store it. My suggestion is to have a specific CPT that later can have its own template on the theme and that could have it's own type of admin (hiding or showing things contextually just for the CPT)

Start by comparing the two referenced Instagram importer approaches: the data-liberation-agent pull request and the instagram-importer repository. Then clarify how imported data should be stored, including whether it uses a dedicated WordPress custom post type with contextual administration and theme support. Done means the import path and storage design are agreed and implemented.

Written by the indexing model from the issue text.