Allow the inherit: keyword to fine tune what will be inherited

Prpoposal

Allow the inherit: to fine tune what will be inherited:

default:
  before_script: echo Hello World
  image: ruby:2.1

variables:
  DOMAIN: my-domain.com
  KEY: value

dast:
  inherit:
    default: [image] # inherit only `image:`, but not `before_script`
    variables: [DOMAIN] # inherit only `DOMAIN`, but not `key`
  script: echo Hello World

Related to: #207484 (closed) and !25690 (merged)