Build linting tools & integrate with GHPages

[ShaneCurcuru]

As a human-curated dataset that's also being used by researchers, we need to ensure the various data models we store as Jekyll frontmatter are linted and are good-enough data values to be used in research.

We need automated commit checks that validate Pages builds as well as the schemas for at least _foundations, _sponsorships, _entities, and any other models we build. Linting tools should be automatically generated to reduce tooling maintenance.

I'd love to have a way to use an openapi spec as the core source, and build linting from that (along with any other data validation kinds of things we need for reports, etc.).

Anyone interested in helping, or showing a model of how to do this?

[ShaneCurcuru]

Note: linting tools should also work with any data quality standards we come up with, as hinted at in issue #8 That is, hints about which data fields are most important for when new users submit a new foundation record, and at least hinting at various other kinds of data validation for string description fields and the like (that might not be doable purely via schema restrictions).