[epic] Support for multiple outputs per prompt

[triathematician]

• [x] Refactor prompt pipeline execution code to support outputs with multiple responses (for same parameters)
  • [x] #58
  • [x] #280
• [x] Add UI parameter for multiple responses, and refactor views to support viewing multiple responses (for same parameters)
  • [x] #290
  • [x] #278
  • [x] #284
  • [x] #285
  • [x] #286