Support for nr-assistant

[Steve-Mcl]

Description

• Adds a assistant to settings
• Performs a one-time settings update when the nr-assistant package is detected but the assistant settings have not yet been written

Related Issue(s)

Checklist

• [x] I have read the contribution guidelines
• [x] Suitable unit/system level tests have been added and they pass
• [ ] Documentation has been updated
  • [ ] Upgrade instructions
  • [ ] Configuration details
  • [ ] Concepts
• [ ] Changes flowforge.yml?
  • [ ] Issue/PR raised on FlowFuse/helm to update ConfigMap Template
  • [ ] Issue/PR raised on FlowFuse/CloudProject to update values for Staging/Production

Labels

• [ ] Includes a DB migration? -> add the area:migration label