[GA4] Add name property to cta_click event

[stephaniehobson]

Description

Add name property to cta_click event.

GA4 default reports make it hard to filter reports by more than one property. To help with self serve reporting (especially for WNPs) we're adding am optional data-cta-name property to the cta_click event. This is intended to contain an identifier unique across the entire site.

I chose name because we already use it in widget_action and did not want the value to be confused with link_id which will contain the HTML id if there is one.

This was requested by @slightlyoffbeat on Slack.

Success Criteria

• Update bedrock docs
• Update GTM config
• Add data-cta-name attributes to WNP132 as test page