TopNavRedesign: Finish migrating to top_nav_view_model

• Requirements (issue)
• Tasks (epic)
• Full Context Spike MR (permanent draft)
• All MR parts ...
  • Introduce top nav helper MR
    • Finish migrating to top_nav_view_model MR (depends on parent MR)

What does this MR do?

In the previous MR we set up the structure for building the top_nav_view_model which powers the FE for the new top nav redesign. This MR fills in the details and finishes migrating over links from the old views.

The HAML files we are migrating over include:

• app/views/layouts/nav/_explore.html.ham for unauthenticated users
• app/views/layouts/nav/_dashboard.html.ham for authenticated users
• app/views/layouts/nav/projects_dropdown/_show.html.haml
• app/views/layouts/nav/groups_dropdown/_show.html.haml

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have not included a changelog entry because No user facing changes.
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Related to #301143 (closed)