Implement analysis helpers for data model

[anngvu]

It is helpful to get a summary analysis report of the data model on certain characteristics, some of which serve as sanity checks. Some of these we'll want to run in the make step when the .jsonld is updated to a new .jsonld.

• Summary of diff on how many classes, properties, enums, etc. were added, removed, or updated (i.e. added new valid value to an enum).
• Summary of total classses, props, etc. in new and current version.
• Pointing out parts of the data model that are not used in templates (maintainer can configure whether they want this to be pointed out or not, depending on how much they care about keeping their data model "lean"). In typical code, when something is declared/imported but not used, this is frowned upon for several reasons. In a data model, it could be mean there was some change made and the old stuff was supposed to be removed but never removed so it could be potentially confusing if it still sticks around.
• Point out if there seems to be too many columns in a template? This might be bad for the user experience.

@cconrad8 @elv-sb touched upon this today as something that would be helpful during the workflow that I'll implement eventually... Let me know if you have specific suggestions and examples from your experience for other analysis things.