Add structured event tracking to Security upgrade banner

What does this MR do and why?

Adds some structured event tracking to the Security upgrade banner as it will help us know whether or not the banner is successfully leading to feature adoption and conversion.

Screenshots or screen recordings

View screen recording on YouTube.

How to set up and validate locally

1. Enable Snowplow Micro for your GDK instance

2. Navigate to a project page for a project within a free group

3. Select the “Security & compliance” side-nav item (either hover or click)

4. Select the “Configuration” sub-item in the “Security & compliance” sub-menu

5. Wait for the banner to load

   • If it doesn’t load, make sure you are viewing a project within an unpaid group (not in a trial)

   • If it still doesn’t load, make sure you’ve cleared any past dismissal of the banner:

     # Get your user id from /-/profile under the Main Settings section
     Users::Callout.where(feature_name: 'security_configuration_upgrade_banner', user_id: <your_user_id>).destroy_all

6. Navigate to your Snowplow Micro instance (http://localhost:9091/micro/good, for example) & check out the tracking events

   • When the banner loads you should see a display_banner event
   • When you click the CTA button, you should see a click_button event
   • When you click the little × to close it, you should see a dismiss_banner event (this will also create the aforementioned Users::Callout record)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #346645 (closed)