Add more filters to dashboard issues refactor

What does this MR do and why?

This MR adds label, milestone, and my reaction filter tokens to the dashboard issues refactor. It also shows an empty state when there is no search query to replicate existing logic.

Behind feature flags vue_issues_dashboard and root_level_issues_query default disabled.

Follow-up MRs will add issue counts etc.

Screenshots or screen recordings

Screen_Recording_2022-12-14_at_4.50.42_pm

How to set up and validate locally

1. In rails console enable the feature flags

   Feature.enable(:vue_issues_dashboard)
   Feature.enable(:root_level_issues_query)

2. Visit the issues dashboard page http://127.0.0.1:3000/dashboard/issues
3. Test searching and filtering in the filter bar

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.