Search Page Vue vertical navigation

What does this MR do and why?

5/7 add vertical navigation vue app

• Search Page vertical navigation search helper (merged)
• Search Page layout changes (merged)
• Move filters into their own component (merged)
• Fix search helper vertical navigation JSON method (merged)
• Search Page Vue vertical navigation (merged) 👈 this MR
  • Fix missing feature flag check in Vue vertical menu (merged)
  • Convert all Search Page RSpecs to support vertical search navigation

Screenshots or screen recordings

before	after

How to set up and validate locally

1. checkout this branch
2. In rails console enable the feature flag

   Feature.enable(:search_page_vertical_nav)

3. Visit search page http://your-gdk.url/search
4. Admire vertical navigation

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 #293740 (closed)