Add chosen custom properties as default columns in every new campaign

Mark a custom property (Settings > Properties) as "default" so it is added as a column to every new campaign sheet automatically, the same way First name, Email and the other built-in properties are. An API endpoint to add a property column to a campaign sheet would cover the same need for automated setups.

Why it helps: Teams that run campaigns via the API or MCP need fields like a HubSpot Contact ID in every campaign so they can import contacts with that data and track the campaign externally.