Fixes for edit user name & email form actions

The `#user_name_path` & `#user_email_path` route helper methods should
require a `user` argument. However, the argument was not provided in
either of the PRs where these forms were added (#2497 & #2509).

The assertions in `Users::NamesControllerTest` &
`Users::EmailsControllerTest` were already comparing with the correct
values and *somehow* the calls to `#user_name_path` & `#user_email_path`
without any arguments were magically returning the correct value, even
though when I try them in a Rails console, I get an
`ActionController::UrlGenerationError`. So this mistake wasn't actually
causing any problems.

app/views/users/emails/edit.html.erb

@@ -51,7 +51,7 @@
 
 <div class="govuk-grid-row">
   <div class="govuk-grid-column-two-thirds">
-    <%= form_for @user, url: user_email_path do %>
+    <%= form_for @user, url: user_email_path(@user) do %>
       <%= render "govuk_publishing_components/components/input", {
         label: {
           text: "Email"

app/views/users/names/edit.html.erb

@@ -40,7 +40,7 @@
 
 <div class="govuk-grid-row">
   <div class="govuk-grid-column-two-thirds">
-    <%= form_for @user, url: user_name_path do |f| %>
+    <%= form_for @user, url: user_name_path(@user) do |f| %>
       <%= render "govuk_publishing_components/components/input", {
         label: {
           text: "Name"