Add to the current JSON export:

• Flow node start and end time

• Ensure all flow nodes are listed (don't group flow nodes).

Original proposal:

API change:

"processInstance": {
  ...,
  "flowNodeInstances": [
    {
      "id": "someId",
      "name": "someId",
      "startDate": "2023-08-03T16:36:57.339+0200",
      "endDate": "2023-08-03T16:36:57.339+0200"
    },
    ...
  ],
  ...
},...

ATs:

• Documentation is updated to reflect change
• Internal API docs updated

Testing Notes:

• In the UI, no new fields are shown for the raw data report
• For CSV export, no new fields are shown
• For Json export, no new fields are included for any report types other than raw data reports
• For Json export, the new fields exist and:
  • The flow node IDs, names, start and end dates are correct
  • Optimize has separate entries even if a flow node has been executed more than once
  • Optimize presents a null flow node end date value if the flow node instance is still running