Use default enabled features in the hints renderer
Use default enabled features in the hints renderer

Summary: SAT uses the `HintsRenderer` manually without going through
`ItemRenderer`, but it doesn't pass in an `enabledFeatures` prop which
broke things. This just sets a sane default prop for those cases.

Test Plan:
 - `make subperseus`
 - Visit http://localhost:8080/mission/sat/tasks/5681726336532480
 - See that I can progress to the next problem without JS errors

Auditors: jared, alex

learningequality/perseus,ariabuckles/perseus,ariabuckles/perseus,ariabuckles/perseus,learningequality/perseus,ariabuckles/perseus