Cache results of search filter field values

[bjester]

Observed behavior

Queries for search filter field values, such as the choices for filtering licenses or content kinds, are queried often and tend to take some time to complete.

Examples:
ContentKinds
Licenses

Expected behavior

Since the results of these queries are unlikely to change with great frequency, we should cache them. For instance, the ContentKinds query returns 8 rows on average-- the entirety of the currently defined content kinds.

User-facing consequences

Slower experience loading the search page. Perhaps slower experience overall if search is actively used

Errors and logs

Additional information

Code