feat(nimbus): add state machine for rollouts

[moibra05]

Because

• Rollouts need dedicated lifecycle transitions, including a rollout specific Disabled state

This commit

• Adds rollout transition forms, views, routes, validation, and test coverage for all valid and invalid rollout state transitions
• Adds the Disabled status and updates rollout state filters
• Stages phase changes until Remote Settings approval, then advances or ends the active phase
• Supports disabling and re-enabling rollouts through the review workflow
• Updates API documentation and model choices

Fixes #15085

[freshstrangemusic]

Only rollouts that are isFirefoxLabsRollout: true can be paused. Regular rollouts do not support pausing enrollments.

[moibra05]

Blocked on mermaid diagram updates