Add any offline data to health check

[rdlrt]

Describe the bug

Currently, Koios endpoints use a balanced approach for health checks to avoid scanning every endpoint, but still poll relevant ones. As such, we do not test pool_offline_data or asset registry cache as part of these polls, but since these do not depend on block/tx/etc, makes sense to add these individually.

Alternately, this would already be solv-able via approach from #26