New Settings Menu, Routes and Controllers Organization (#641)

* Add new settings routes and controllers

* Add new settings view, restructure controllers and routes

* Fix lint errors

test/controllers/settings/notifications_controller_test.rb

@@ -0,0 +1,11 @@
+require "test_helper"
+
+class Settings::NotificationsControllerTest < ActionDispatch::IntegrationTest
+  setup do
+    sign_in users(:family_admin)
+  end
+  test "get" do
+    get settings_notifications_url
+    assert_response :success
+  end
+end