Refactor direction stages to pull from data files

Why is this change being made?

Refactor direction generator so that it pulls the list of sections and stages from the YAML files instead of it being manually listed. Some stages' direction folders needed to be moved as it needs to match the slug and be in the direction/ folder. Redirects have been added. Some stages do not have a direction page so a placeholder is added, but redirected as well.

Related to Product#14015 (closed)

Also removes data and code related to SEGs.

Validation

Content should not be different as this is a refactor, except for the removal of SEG.

Before	After
Direction DevOps stages: https://about.gitlab.com/direction/	https://refactor-direction-stages.about.gitlab-review.app/direction/
Dev direction what's next: https://about.gitlab.com/direction/dev/	https://refactor-direction-stages.about.gitlab-review.app/direction/dev/

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Commits

• Refactor to use data files

• Remove deprecated SEG

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