emails: add /emails index page.

Add emails index page at https://danbooru.donmai.us/emails. Mods can use
this page to view and search emails belonging to users below mod level.

app/views/emails/index.html.erb

@@ -0,0 +1,32 @@
+<div id="c-emails">
+  <div id="a-index">
+    <%= search_form_for(emails_path) do |f| %>
+      <%= f.simple_fields_for :user do |fa| %>
+        <%= fa.input :name, label: "User Name", input_html: { value: params.dig(:search, :user, :name), "data-autocomplete": "user" } %>
+      <% end %>
+
+      <%= f.input :address_ilike, label: "Address", input_html: { value: params[:search][:address] }, hint: "Use * for wildcard" %>
+      <%= f.input :is_verified, label: "Verified?", collection: %w[Yes No], selected: params[:search][:is_verified] %>
+      <%= f.submit "Search" %>
+    <% end %>
+
+    <%= table_for @email_addresses, class: "striped autofit" do |t| %>
+      <% t.column :user do |email| %>
+        <%= link_to_user email.user %>
+      <% end %>
+      <% t.column :address %>
+      <% t.column :is_verified, name: "Verified?" do |email| %>
+        <% if email.is_verified? %>
+          <%= link_to "Yes", emails_path(search: { is_verified: true }) %>
+        <% else %>
+          <%= link_to "No", emails_path(search: { is_verified: false }) %>
+        <% end %>
+      <% end %>
+      <% t.column :updated_at, name: "Updated" do |email| %>
+        <%= time_ago_in_words_tagged(email.updated_at) %>
+      <% end %>
+    <% end %>
+
+    <%= numbered_paginator(@email_addresses) %>
+  </div>
+</div>

app/views/static/site_map.html.erb

@@ -154,6 +154,10 @@
           <li><%= link_to("Moderation Reports", moderation_reports_path) %></li>
         <% end %>
 
+        <% if policy(EmailAddress).index? %>
+          <li><%= link_to("Email Addresses", emails_path) %></li>
+        <% end %>
+
         <% if policy(IpAddress).index? %>
           <li><%= link_to("IP Addresses", ip_addresses_path) %></li>
         <% end %>