support previewing existing campaign plans
Created by: sqs
Adds a new GraphQL API field CampaignPlan.previewURL
that returns a URL to the CampaignDetails page (/campaigns/new?plan=...
) that shows the diffs and changesets for an existing campaign plan.
This makes it so that API clients (such as the src
CLI) can create campaign plans programmatically (eg using createCampaignPlanFromPatches
) but still allow users to visually preview them before creating the campaign.