hide_in_dropdown flag for networks

apps/block_scout_web/lib/block_scout_web/templates/layout/_footer.html.eex

@@ -37,7 +37,7 @@
           <li><a href="https://forum.poa.network/c/blockscout" rel="noreferrer" class="footer-link"><%= gettext("Support") %></a></li>
         </ul>
       </div>
-      <% main_nets = main_nets() %>
+      <% main_nets = main_nets(other_networks()) %>
 
       <%= unless Enum.empty?(main_nets) do %>
         <div class="col-md-<%= col_size %> footer-list">
@@ -50,7 +50,7 @@
         </div>
       <% end %>
 
-      <% test_nets = test_nets() %>
+      <% test_nets = test_nets(other_networks()) %>
 
       <%= unless Enum.empty?(test_nets) do %>
         <div class="col-md-<%= col_size %> footer-list">

apps/block_scout_web/lib/block_scout_web/templates/layout/_topnav.html.eex

@@ -85,15 +85,15 @@
           </a>
           <div class="dropdown-menu" aria-labelledby="navbarDropdown">
             <a class="dropdown-item header division">Mainnets</a>
-            <%= for %{url: url, title: title} <- head_main_nets() do %>
+            <%= for %{url: url, title: title} <- dropdown_head_main_nets() do %>
               <a class="dropdown-item" href="<%= url%>"><%= title %></a>
             <% end %>
             <a class="dropdown-item header division">Testnets</a>
-            <%= for %{url: url, title: title} <- test_nets() do %>
+            <%= for %{url: url, title: title} <- test_nets(dropdown_nets()) do %>
               <a class="dropdown-item" href="<%= url%>"><%= title %></a>
             <% end %>
             <a class="dropdown-item header division">Other networks</a>
-            <%= for %{url: url, title: title} <- other_nets() do %>
+            <%= for %{url: url, title: title} <- dropdown_other_nets() do %>
               <a class="dropdown-item" href="<%= url%>"><%= title %></a>
             <% end %>
           </div>

apps/block_scout_web/lib/block_scout_web/views/layout_view.ex

@@ -154,38 +154,47 @@ defmodule BlockScoutWeb.LayoutView do
   def ignore_version?(_), do: false
 
   def other_networks do
-    if Application.get_env(:block_scout_web, :other_networks) do
-      :block_scout_web
-      |> Application.get_env(:other_networks)
-      |> Poison.decode!()
-      |> Kernel.||(@default_other_networks)
-      |> Enum.map(fn chain ->
-        for {key, val} <- chain, into: %{}, do: {String.to_atom(key), val}
-      end)
-    else
-      @default_other_networks
-    end
+    get_other_networks =
+      if Application.get_env(:block_scout_web, :other_networks) do
+        :block_scout_web
+        |> Application.get_env(:other_networks)
+        |> Poison.Parser.parse!(%{keys: :atoms!})
+      else
+        @default_other_networks
+      end
+
+    get_other_networks
     |> Enum.reject(fn %{title: title} ->
       title == subnetwork_title()
     end)
     |> Enum.sort()
   end
 
-  def main_nets do
-    Enum.reject(other_networks(), &Map.get(&1, :test_net?))
+  def main_nets(nets) do
+    nets
+    |> Enum.reject(&Map.get(&1, :test_net?))
   end
 
-  def head_main_nets do
-    main_nets()
-    |> Enum.reject(&Map.get(&1, :other?))
+  def test_nets(nets) do
+    nets
+    |> Enum.filter(&Map.get(&1, :test_net?))
+  end
+
+  def dropdown_nets do
+    other_networks()
+    |> Enum.reject(&Map.get(&1, :hide_in_dropdown?))
   end
 
-  def test_nets do
-    Enum.filter(other_networks(), &Map.get(&1, :test_net?))
+  def dropdown_head_main_nets do
+    dropdown_nets()
+    |> main_nets()
+    |> Enum.reject(&Map.get(&1, :other?))
   end
 
-  def other_nets do
-    Enum.filter(other_networks(), &Map.get(&1, :other?))
+  def dropdown_other_nets do
+    dropdown_nets()
+    |> main_nets()
+    |> Enum.filter(&Map.get(&1, :other?))
   end
 
   def other_explorers do