Add Snowplow tracking to the "user_bar"

What does this MR do and why?

Adds Snowplow tracking events to the user bar links:

• Issues link
• MRs dropdown
• Assigned MRs link
• Review requests link
• TODOs link

Screenshots or screen recordings

No visual change

How to set up and validate locally

1. Enable the new nav:

   1. Enable the feature flag:

      echo "Feature.enable(:super_sidebar_nav)" | rails c

   2. Enable the user setting from the user dropdown:

      

2. Setup Snowplow micro: https://gitlab.com/gitlab-org/gitlab-development-kit/-/blob/main/doc/howto/snowplow_micro.md
3. Install the Snowplow Analytics Debugger extension.
4. Click on the tracked elements.

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 #402716 (closed)