Dataset list expansion

[mdrum]

The dataset lists on the context objects are currently filtered by these parameters:

1. Dataset must be a PDS4 Bundle
2. Datasets must directly reference that target/spacecraft/instrument
3. Dataset must not reference something further down the chain (a dataset that references an instrument will not show up on a spacecraft or target page, and one that references a spacecraft won't show up on the target page)

In practice, this effectively filters out almost all datasets to the point of undiscoverability, and has proven confusing to reviewers of the site. There are currently more context objects than PDS4 bundles, so almost all pages are empty.

We should design a new interactive interface for each of the context object pages that displays datasets that meet fewer of those requirements, and also gives more contextual metadata for each inline. For example, a user visiting the InSight page might expect to see the datasets associated with each of the instruments directly from this page. Reviewers have also indicated that they would have expected datasets listed on the Target pages that belong to specific missions.