Global Search New Navigation - part 2

What does this MR do and why?

Adds the main part of the left menu for the advanced search page.

• New navigation component
• New navigation component test
• app.vue condition to allow switching between old and new

MR sequence	status
1. Global Search New Navigation - fundation	in review
2. Global Search New Navigation - part 1	in review
3. Global Search New Navigation - state	in review
4. Global Search New Navigation - part 2	in review 👈 this
5. Global Search New Navigation - part 3	in review

Screenshots or screen recordings

before	after

How to set up and validate locally

1. Setup the Advanced Search https://gitlab.com/gitlab-org/gitlab-development-kit/blob/main/doc/howto/elasticsearch.md
2. Enable the Advanced Search http://gdk:3000/admin/application_settings/advanced_search
3. Enable and turn on the new left sidebar
4. Visit the search page: http://gdk:3000/search

Validation:

1. Visit the search page: http://gdk:3000/search with Advanced Search enabled
2. Visit the search page with Advanced Search disabled
3. Test the code search for filters
4. Test the issues search for filters

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 #382328 (closed)