Introduce Govern Stage

Why is this change being made?

For context on this MR, please reference https://gitlab.com/gitlab-com/Product/-/issues/4792+.

This MR makes the following changes:

1. Removes the current Protect stage.
2. Adds a new Govern stage.
3. Adjusts the DevOps diagram to position Manage as a foundational stage, and Govern as an overarching stage across the DevOps lifecycle.
4. Moves the Manage:Compliance group over to Govern:Compliance.
5. Moves the former Protect:Container Security:Container Scanning category over to Secure:Composition Analysis:Container Scanning.
6. Moves the former Protect:Container Security:Security Orchestration category over to Govern:Security Policies:Security Policy Management.
7. Moves the Secure:Threat Insights group over to Govern:Threat Insights.
8. Creates a new Dependency Management category under the Govern:Threat Insights group.

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