text: Title: Cases plugin needs to export some more types publically
  Body: Run `node scripts/build_api_docs --stats exports --plugin cases` to see the list:
  
  ```
   7 referenced API items not exported
  ┌─────────┬───────────────────────────────────────────┬──────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
  │ (index) │            Not exported source            │                                                    references                                                    │
  ├─────────┼───────────────────────────────────────────┼──────────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
  │    0    │       'cases-public-AllCasesProps'        │              'cases-def-public.CasesUiStart.getAllCases, cases-def-public.CasesUiStart.getAllCases'              │
  │    1    │ 'cases-public-AllCasesSelectorModalProps' │ 'cases-def-public.CasesUiStart.getAllCasesSelectorModal, cases-def-public.CasesUiStart.getAllCasesSelectorModal' │
  │    2    │       'cases-public-CaseViewProps'        │              'cases-def-public.CasesUiStart.getCaseView, cases-def-public.CasesUiStart.getCaseView'              │
  │    3    │    'cases-public-ConfigureCasesProps'     │        'cases-def-public.CasesUiStart.getConfigureCases, cases-def-public.CasesUiStart.getConfigureCases'        │
  │    4    │      'cases-public-CreateCaseProps'       │            'cases-def-public.CasesUiStart.getCreateCase, cases-def-public.CasesUiStart.getCreateCase'            │
  │    5    │      'cases-public-RecentCasesProps'      │           'cases-def-public.CasesUiStart.getRecentCases, cases-def-public.CasesUiStart.getRecentCases'           │
  │    6    │        'cases-server-CasesClient'         │                               'cases-def-server.CaseRequestContext.getCasesClient'                               │
  ```
  
  Without exporting these types publically they won't show up in our API documentation:
  
  <img width="844" alt="Screen Shot 2021-05-06 at 4 35 40 PM" src="https://user-images.githubusercontent.com/16563603/117362490-53866000-ae89-11eb-802e-1d503de55294.png">
  