Force job
- it automatically forces the refresh of a /first-rows entry if it's missing but should exist
- it adds two endpoints (behind authentication) to force the refresh of cache entries:
  - `POST /admin/force-refresh/splits?dataset={dataset}`
  - `POST /admin/force-refresh/first-rows?dataset={dataset}&config={config}&split={split}`

See #640
Force job: - it automatically forces the refresh of a /first-rows entry if it's missing but should exist
- it adds two endpoints (behind authentication) to force the refresh of cache entries:
  - `POST /admin/force-refresh/splits?dataset={dataset}`
  - `POST /admin/force-refresh/first-rows?dataset={dataset}&config={config}&split={split}`

See #640