Maintain /assets/v5.0.0/images for St Edward’s Crown

This change prevents the new crown image assets being copied from v5.1.0+ and leaves Metalsmith to copy committed v5.0.0 assets from `src/assets` instead

1. Use `/assets/images` for new crown
2. Use `/assets/v5.0.0/images` for old crown

lib/metalsmith.js

@@ -134,11 +134,18 @@ module.exports = metalsmith
     }
 
     await Promise.all([
+      // GOV.UK Frontend `/assets/images` use new crown
       copyAssets('{fonts/*,images/*,manifest.json}', {
         cwd: join(dirname(require.resolve('govuk-frontend')), 'assets'),
         dest: 'assets'
       }),
 
+      // GOV.UK Frontend `/assets/v5.0.0/images` use old crown via `src/assets`
+      copyAssets('{fonts/*,manifest.json}', {
+        cwd: join(dirname(require.resolve('govuk-frontend')), 'assets'),
+        dest: 'assets/v5.0.0'
+      }),
+
       copyAssets('govuk-frontend.min.css?(.map)', {
         cwd: dirname(require.resolve('govuk-frontend')),
         dest: 'stylesheets'