Add remote instance immersive view instance controls

[cstns]

Description

WIP

Related Issue(s)

closes #6649

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 (c19da93) to head (aa4d24f).

Additional details and impacted files

@@                                        Coverage Diff                                        @@
##           6645_handle-redirect-when-accessing-unreachable-remote-instances    #6652   +/-   ##
=================================================================================================
  Coverage                                                             76.66%   76.66%           
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  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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