Add custom hostname support to Instances

[hardillb]

Description

UI work for #324

Will also include the ee work

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

Labels

• Backport needed? -> add the backport label
• Includes a DB migration? -> add the area:migration label

[codecov]

Codecov Report

Attention: Patch coverage is 19.26606% with 88 lines in your changes missing coverage. Please review.

Project coverage is 78.52%. Comparing base (b622261) to head (8a3dd0f).
Report is 96 commits behind head on main.

Files	Patch %	Lines
forge/ee/routes/customHostnames/index.js	12.98%	67 Missing ⚠️
forge/ee/lib/customHostnames/index.js	23.52%	13 Missing ⚠️
forge/db/models/ProjectSettings.js	25.00%	3 Missing ⚠️
forge/db/views/Project.js	50.00%	2 Missing ⚠️
forge/routes/api/project.js	0.00%	2 Missing ⚠️
forge/routes/api/settings.js	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3830      +/-   ##
==========================================
- Coverage   79.28%   78.52%   -0.77%     
==========================================
  Files         281      284       +3     
  Lines       12755    12945     +190     
  Branches     2844     2886      +42     
==========================================
+ Hits        10113    10165      +52     
- Misses       2642     2780     +138     

Flag	Coverage Δ
backend	78.52% <19.26%> (-0.77%)	⬇️

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[knolleary]

Going to hit merge once tests pass