Fix RBAC permission check for inflight messages

[Steve-Mcl]

Description

The RBAC permission check for inflight channel messages now only applies when the entityType is one of 'p', 'd', or 'a'.
This prevents an error where no application is expected.

Related Issue(s)

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
• Link to Changelog Entry PR, or note why one is not needed.

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 76.58%. Comparing base (abe7b49) to head (0b6a5ac).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7641   +/-   ##
=======================================
  Coverage   76.58%   76.58%           
=======================================
  Files         413      413           
  Lines       21845    21845           
  Branches     5757     5757           
=======================================
  Hits        16730    16730           
  Misses       5115     5115           

Flag	Coverage Δ
backend	76.58% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Steve-Mcl]

flaky admin.spec.js test (nothing changed in there!)