EE port of 52385-search-bar-for-dashboard-list

app/assets/javascripts/init_legacy_filters.js

app/assets/javascripts/pages/dashboard/issues/index.js

...ssets/javascripts/pages/dashboard/merge_requests/index.js

app/assets/javascripts/search_autocomplete.js

app/controllers/dashboard_controller.rb

app/controllers/root_controller.rb

app/helpers/application_helper.rb

app/helpers/dashboard_helper.rb

app/helpers/search_helper.rb

app/views/dashboard/issues.html.haml

app/views/dashboard/merge_requests.html.haml

app/views/shared/issuable/_filter.html.haml

app/views/shared/issuable/_search_bar.html.haml

...gelogs/unreleased/52385-search-bar-for-dashboard-list.yml

doc/user/search/img/dashboard_links.png

doc/user/search/img/issues_assigned_to_you.png

doc/user/search/img/left_menu_bar.png

doc/user/search/index.md

ee/app/helpers/ee/search_helper.rb

spec/controllers/root_controller_spec.rb