Draft: WIP POC auto cancel redundant pipelines with workflow

What does this MR do and why?

Warning: This is just a POC MR. Code quality and tests are broken.

I created this POC spike MR to show how the "Auto-cancel redundant pipelines" would work with the new workflow:auto_cancel keyword.

Related to #412473 (closed)

Example config;

workflow:
  auto_cancel:
    on_new_commit: interruptible # options: "interruptible", "conservative", "none"

build1:
  stage: build
  script: sleep 30

build2:
  stage: build
  script: sleep 30
  interruptible: false

test1:
  stage: test
  script: sleep 30

test2:
  stage: test
  script: sleep 30
  interruptible: false

deploy1:
  stage: deploy
  script: sleep 30

deploy:
  stage: deploy
  script: sleep 30
  interruptible: false

While this pipeline is running;

If you send another commit to the same branch, the interruptible jobs will be canceled

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