Move NHS.UK component css into nhsuk.css (#120)

This moves the `.nhsuk-list--border` and `.nhsuk-related-nav` css into
the `nhsuk.scss` file, along with the other NHS website-only CSS.

This means that the compiled `main.css` file is slightly smaller, as
that doesn’t use those 2 components, and the code is only used in the
example nhsu.uk template pages, which include the additional compiled
`nhsuk.css` file.

A minor bit of tidying-up, but should help us be less confused in
future.

app/assets/sass/main.scss

@@ -2,8 +2,6 @@
 @import 'node_modules/nhsuk-frontend/packages/nhsuk';
 
 // Components that are not in the NHS.UK frontend library
-@import 'components/list-border';
-@import 'components/related-nav';
 @import 'components/figure';
 
 ///////////////////////////////////////////

app/assets/sass/nhsuk.scss

@@ -1,4 +1,11 @@
-@import 'node_modules/nhsuk-frontend/packages/core/settings/colours';
+@import 'node_modules/nhsuk-frontend/packages/core/settings/all';
+@import 'node_modules/nhsuk-frontend/packages/core/tools/all';
+
+// NHS.UK website template styles
+//
+// This CSS is all used to re-create some of the NHS.UK website
+// styles within the example templates. It will likely need updating
+// as the NHS.UK website updates.
 
 // ==========================================================================
 // Log in link
@@ -92,7 +99,7 @@
   }
  }
 
- 
+
 // ==========================================================================
 // Feedback form
 // ==========================================================================
@@ -600,3 +607,38 @@ main .app-list-signage a[href=""]:focus {
 main .app-list-signage a[href=""] {
   color: $color_nhsuk-white;
 }
+
+// ==========================================================================
+// COMPONENTS / #RELATED-NAV
+// ==========================================================================
+
+.nhsuk-related-nav {
+  border-top: 1px solid $nhsuk-border-color;
+
+  @include mq($until: desktop) {
+    margin-top: nhsuk-spacing(7);
+  }
+}
+
+.nhsuk-related-nav__heading {
+  @include nhsuk-typography-responsive(19, $override-line-height: 1.2);
+
+  margin-bottom: 12px;
+  padding-top: nhsuk-spacing(3);
+}
+
+.nhsuk-related-nav__list {
+  @include nhsuk-typography-responsive(16);
+
+  list-style: none;
+  padding-left: 0;
+}
+
+// ==========================================================================
+// COMPONENTS / #LIST-BORDER
+// ==========================================================================
+
+.nhsuk-list--border li {
+  border-bottom: 1px solid $color_nhsuk-grey-4;
+  padding: 8px 0 16px;
+}