Swap maps with arrays on the applications page

[cstns]

Description

use arrays instead of maps for application devices and instances on the applications page

Related Issue(s)

part of #4014

Checklist

• I have read the contribution guidelines
• 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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.76%. Comparing base (8718b1d) to head (9432591).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4148   +/-   ##
=======================================
  Coverage   78.76%   78.76%           
=======================================
  Files         286      286           
  Lines       13053    13053           
  Branches     2910     2910           
=======================================
  Hits        10281    10281           
  Misses       2772     2772           

Flag	Coverage Δ
backend	78.76% <ø> (ø)

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