Add Learn more link to the Visitor Groups banner notification on dashboard

[wpdarren]

Bug Description

On the Audience Segmentation (Visitor Groups) Banner notification on the dashboard, we should add a Learn more link to point users to the Site Kit documentation for this feature. This should behave the same as other learn more links but point to https://sitekit.withgoogle.com/documentation/using-site-kit/visitor-groups/ The link should open up in a new window, and include the external link icon. We should also create a GA event for the link to be triggered when clicked.

Edit: Props to @desrosj -- @jimmymadon we should add a learn more link on the settings page as it also lacks additional context for the Visitor Groups feature. Interested in your thoughts if this could be included in this work, or, would you prefer I created a new ticket for this. Thanks!

Steps to reproduce

1. Set up Site Kit with Analytics for a property that has zero or real data.
2. Observe the Learn how different types of visitors interact with your site banner on the dashboard.
3. Note that you will have to refresh the dashboard for it to appear.

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Acceptance criteria

• A "Learn more" link that points to https://sitekit.withgoogle.com/support?doc=visitor-groups should be added to:

  • the description of the Audience Segmentation Setup CTA
    

  • the Visitor groups setup CTA in Admin Settings.
    

Implementation Brief

• Fix VRTs for attached PR which does the following:
  • Use the getDocumentationLinkURL( 'visitor-groups' ) from the CORE_SITE datastore to create the link and pass it to the CTAs mentioned in the ACs.

Test Coverage

• No new tests required.

QA Brief

Changelog entry

[desrosj]

I was looking to report that the settings page lacked additional context for the Visitor Groups feature. This could probably be handled at the same time.

[wpdarren]

@desrosj thanks for the comment!

Yes, I agree a learn more link would be user-friendly there too. I will update the ticket to include this.

[jimmymadon]

@marrrmarrr Since this is UX change and perhaps was discussed before, could you please confirm if adding a "Learn more" link to the "Visitor Groups" documentation in the Dashboard Setup CTA and Admin Settings CTAs is fine here?

c.c. @sigal-teller @techanvil

[marrrmarrr]

@jimmymadon this sounds like a good idea, it would help people who don't have context learn about the feature and potentially make up their mind if it's helpful for them.

[jimmymadon]

AC + IB ✅ Moving this to EB since Mariya has approved this and is quite straightforward.