bug-fixes:  audio and participant stat

- add has_null_status (audio and participant) to test_entry_*_transcribe
  twig files to programatically control UI navigation button enable states
- use slot_refresh on test_entry_transcribe as required for
  audio and participant status's
- fix REY test variant word entry UI response when entry is not a known
  variant: corresponding 'no' radio option is programatically selected