Editor configuration from process environment

[andreikop]

Description

When Flowforge works in K8s cluster, it might be necessary to set some K8S cluster specific settings of editor instances created by FF.
Those settings are likely to be generated by deployment scripts and set by DevOpses, not by team administrators on WebUI, therefore we think that is is most convenient to store in in flowforge process environment but not in the database.

This PR adds next settings:

• INGRESS_CLASS_NAME - Ingress class name for editor instances
• INGRESS_ANNOTATIONS - Ingress annotations for editor instances as JSON-encoded object
• DEPLOYMENT_TOLERATIONS - Editor Deployment tolerations as JSON-encoded object

The changes are backward compatible.
PR for FF Helm which allows to set those settings TBD.

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 flowforge/helm to update ConfigMap Template
  • Issue/PR raised on flowforge/CloudProject to update values for Staging/Production

Labels

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

[hardillb]

@andreikop Can you look at my comments please, I'd like to get this merged today ahead of the release next week.

Thanks