Add ARIA role and ARIA label to admin search form

This way screen reader users will have an easier access to it.

app/components/admin/search_component.html.erb

@@ -1,7 +1,7 @@
 <div class="small-12 medium-6">
-  <%= form_tag(url, method: :get) do |f| %>
+  <%= form_tag(url, method: :get, role: "search") do |f| %>
     <div class="input-group">
-        <%= text_field_tag :search, search_terms.to_s, placeholder: t("admin.shared.user_search.placeholder") %>
+        <%= text_field_tag :search, search_terms.to_s, placeholder: label, "aria-label": label %>
       <div class="input-group-button">
         <%= submit_tag t("admin.shared.user_search.button"), class: "button" %>
       </div>

app/components/admin/search_component.rb

@@ -10,4 +10,8 @@ class Admin::SearchComponent < ApplicationComponent
     def search_terms
       params[:search]
     end
+
+    def label
+      t("admin.shared.user_search.placeholder")
+    end
 end