Organize coverage dirs (#1695)

* Add `Presenters` group to SimpleCov configuration

* Move validators to app/validators, add to simplecov config

app/validators/url_validator.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class UrlValidator < ActiveModel::EachValidator
+  def validate_each(record, attribute, value)
+    record.errors.add(attribute, I18n.t('applications.invalid_url')) unless compliant?(value)
+  end
+
+  private
+
+  def compliant?(url)
+    parsed_url = Addressable::URI.parse(url)
+    !parsed_url.nil? && %w(http https).include?(parsed_url.scheme) && parsed_url.host
+  end
+end