Use an HTTPS Agent and HTTPS scheme if RED.settings.https is set

[Steve-Mcl]

fixes #1473

Description

Supersedes #1480

• Checks RED.settings.https is "something" and if yes:
  • switches the URL scheme to "https://"
  • Adds an HTTPS Agent & spreads whatever is in RED.settings.https into the Agent (permitting any extras to be included or to override the default rejectUnauthorized: false if so desired)

NOTE:

I have tested a variation of this code on a users VM (thanks for the support @Paul-Reed)
By variation, I mean an older branch but the relevant parts of this PR were used and verified.

Related Issue(s)

#1473

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

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