Add support for setting apiMaxLength

[hardillb]

fixes #590

Description

adds support for increasing the apiMaxLength Node-RED settings (also sets the max dashboard payload for file uploads) This matches hosted instance settings.

There will be a matching FlowFuse PR to add the settings to the UI

Related Issue(s)

#590

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

[hardillb]

depends on FlowFuse/flowfuse#6799

[Steve-Mcl]

oh - wait

[hardillb]

@Steve-Mcl what are we waiting for? I've fixed the tests

[Steve-Mcl]

Since I struggled to parse this all back into my head i pulled and wrote a unit test:

File test/unit/lib/template-settings_spec.js

  template-settings
    ✔ should set the apiMaxLength and ui.maxHttpBufferSize option if provided

[Steve-Mcl]

@hardillb

Please check the test I have written in https://github.com/FlowFuse/device-agent/pull/592/changes#diff-6d9077f85bcb74eefb87763266aa0e5ad4d2d22ee063aa6b0eb5022173ad99f7

I believe this is the correct order of events but as you have been in this area i need you to double check it.

I will pre-approve the PR on the assumption my assumptions were right ;)