ci: "upstream" packages validation workflow

[ppawlowski]

Description

This pull request extends the existing Create pre-staging environment workflow by adding the possibility to test upstream packages on pre-staging environment.
In this iteration, the following packages can be verified:

• flowfuse/driver-k8s
• flowfuse/nr-launcher

Major changes:

• publish_k8s_driver and publish_nr_launcher jobs - responsible for building and publishing driver-k8s and nr-launcher node packages when other than the default branch is specified for a particular package
• build-node-red, upload-node-red and create-custom-stack jobs - responsible for building and publishing Node-RED container image as well as creating custom Stack on pre-staging environment to be consumed after login to the FlowFuse pre-staging instance. Executed if the nr-launcher package is about to be verified.
• Introduced Node-RED dockerfile and supporting files to build NR container without pulling the whole flowfuse/helm repository. This may change in the future, though.

Additionally, workflow received a bunch of improvements around conditional statements for particular jobs. All of the changes ensure that core functionality will work as previously and no additional jobs won't be executed.

Related Issue(s)

https://github.com/FlowFuse/CloudProject/issues/389

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