Add redirect support in VS/VSR

[Dean-Coakley]

Proposed changes

• Add an action redirect which allow redirection of http traffic to https to be configured in the VirtualServer.

Example configuration:

action:
  redirect:
    code: 301
    url: http://www.nginx.org 

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto master
• I will ensure my PR is targeting the master branch and pulling from my branch from my own fork

[Rulox]

Added a few suggestions, otherwise looks good! 🚢

[pleshakov]

Added a number of suggestions and consistency notes

[pleshakov]

@Dean-Coakley looks good to me. Please take a look at the renaming suggestion before merging?
@Rulox could you take a look one more time?

[Rulox]

lgtm