POC: immersive editor refactor

[cstns]

Description

The UI was altered by poking it with a very big dev stick. It should in no way or form be merged.

Upsides are:

• Allows for a more integrated Node-RED immersive editor experience in FlowFuse
• Better continuity from app to editor with FlowFuseLess context switchingAllows for pinning the drawer, as we are dealing with an iframe situation (otherwise you get this situation: Make immersive editor drawer have pin/unpin and more responsive to browser sizes/resizing #6318 (comment))
• no context switching required when dealing with the FlowFuse expert or instance menus in the Node-RED experience (currently drawer always overlays)

Related Issue(s)

N/A

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 76.66%. Comparing base (000aa64) to head (3e20506).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6585   +/-   ##
=======================================
  Coverage   76.66%   76.66%           
=======================================
  Files         398      398           
  Lines       20103    20103           
  Branches     4841     4841           
=======================================
  Hits        15411    15411           
  Misses       4692     4692           

Flag	Coverage Δ
backend	76.66% <ø> (ø)

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