Fix Preview and Launch state synchronization

[data-sync-user]

Make sure Preview and Launch controls always reflect the latest saved and unsaved rollout state.

• When a rollout is ready show both Preview and Launch actions.
• If a user changes something such as adding a screenshot and then sends the rollout to Preview without explicitly saving first, the validation/sidebar state should still update correctly
• Any action that performs a server round trip should update the sidebar and rollout validation state
• Add the missing Cancel action after requesting Launch.

┆Issue is synchronized with this Jira Task