Add GA event tracking for the RRM express setup flow

Feature Description

GA event tracking should be added to the RRM express setup flow itself, covering both the flow as a whole and the steps within it:

• Starting, completing and exiting the flow.
• Starting and completing each step.
• The "Learn more" link within a step.
• The "Create new publication" and "Use existing publication" links that switch between the two publication setup paths.

The create and connect paths should be distinguished in the events. create-publication is not a routing step, so it is composed as the event label when the user is on the create path.

• See relevant section in the design doc.
• See the GA events sheet.

Do not alter or remove anything below. The following sections will be managed by moderators only.

Acceptance criteria

The following GA events should be tracked for the RRM express setup flow. All share the category {viewContext}_rrm-express-setup_{ctaSlug}, where {ctaSlug} is the CTA being set up. See the GA events sheet.

• The label is the step slug, with the exception of create-publication, which is not a step of its own and is reported by the publication setup step while the create form is shown.
• complete_step for the setup-complete step is tracked when the user clicks "Return to Dashboard", the step's forward action.
• click_learn_more_link is tracked in each step that offers a "Learn more" link.
• The events above are tracked only with the rrmExpressSetup feature flag enabled.

Implementation Brief

Test Coverage

QA Brief

Changelog entry

No source files or tests are named. Start by locating the RRM express setup flow and existing GA event tracking, then map the acceptance-criteria table to each flow, step, link, and publication path; done means all listed events use the required category and labels only when the rrmExpressSetup feature flag is enabled.