Search Page layout changes

What does this MR do and why?

2/5 Update to the layout of a search page

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

Screenshots or screen recordings

ff disabled	ff enabled

before	with FF	without FF

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 a search page such as http://gdk.test/search

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)