Account layout for "manage your account" active

When the account layout template renders with a nav, the "Your account"
nav option is selected by default.

Some pages which use the account layout belong under "Manage your
account" instead of "Your account".

This allows us the option to render the account layout with "Manage your
account" selected/active in the account nav, instead of the default
"Your account".

app/controllers/root_controller.rb

@@ -25,6 +25,7 @@ class RootController < ApplicationController
     campaign
     gem_layout
     gem_layout_account_manager
+    gem_layout_account_manager_manage_your_account_active
     gem_layout_account_manager_no_nav
     gem_layout_explore_header
     gem_layout_full_width

app/views/root/_account.html.erb

@@ -1,10 +1,11 @@
 <%
   omit_account_navigation ||= nil
+  account_nav_location ||= "your-account"
   di_location = "https://signin.account.gov.uk"
 %>
 
 <%= render partial: "gem_base", locals: {
-  account_nav_location: "your-account",
+  account_nav_location: account_nav_location,
   omit_feedback_form: true,
   omit_footer_border: true,
   omit_global_banner: true,

app/views/root/_gem_base.html.erb

@@ -47,6 +47,7 @@
         module: "explicit-cross-domain-links",
         link_for: "accounts-signed-in",
       },
+      active: show_account_layout,
     },
     {
       text: "Sign out",

app/views/root/gem_layout_account_manager_manage_your_account_active.html.erb

@@ -0,0 +1,3 @@
+<%= render partial: "account", locals: {
+  account_nav_location: "manage",
+} %>

docs/slimmer_templates.md

@@ -20,6 +20,9 @@ This layout omits the default feedback component for GOVUK as the account pages
 
 Same as the `gem_layout_account_manager`, but displays without the account nav component.
 
+## `gem_layout_account_manager_manage_your_account_active`
+
+Same as the `gem_layout_account_manager`, but displays "Manage your account" as active in the [account navigation component](https://components.publishing.service.gov.uk/component-guide/layout_for_public/with_current_account_navigation/preview).
 
 ## `core_layout` (default)