Extract component to render a list of links

This way it's easier to refactor it and/or change it.

Back in commit c156621a4 I wrote:

> Generally speaking, I'm not a big fan of helpers, but there are
> methods which IMHO qualify as helpers when (...) many Rails helpers,
> like `tag`, follow these principles.

It's time to modify these criteria a little bit. In some situations,
it's great to have a helper method so it can be easily used in view
(like `link_to`). However, from the maintenance point of view, helper
methods are usually messy because extracting methods requires making
sure there isn't another helper method with that name.

So we can use the best part of these worlds and provide a helper so it
can be easily called from the view, but internally make that helper
render a component and enjoy the advantages associated with using an
isolated Ruby class.

app/components/shared/link_list_component.rb

@@ -0,0 +1,26 @@
+class Shared::LinkListComponent < ApplicationComponent
+  attr_reader :links, :options
+
+  def initialize(*links, **options)
+    @links = links
+    @options = options
+  end
+
+  def render?
+    links.select(&:present?).any?
+  end
+
+  def call
+    tag.ul(options) do
+      safe_join(links.select(&:present?).map do |text, url, current = false, **link_options|
+        tag.li(({ "aria-current": true } if current)) do
+          if url
+            link_to text, url, link_options
+          else
+            text
+          end
+        end
+      end, "\n")
+    end
+  end
+end