Update templates page

Includes:
- changes to the govukCheckboxesField class
  to allow params to be extended at render time
- updates to templates and folders CSS

app/assets/stylesheets/components/message.scss

@@ -24,6 +24,9 @@
   }
 }
 
+$message-text-left-spacing: 22px;
+$message-type-bottom-spacing: govuk-spacing(4);
+
 .message {
 
   &-name {
@@ -63,23 +66,14 @@
   }
 
   &-type {
-    color: $secondary-text-colour;
-    margin: 0 0 govuk-spacing(4) 0;
+    color: $govuk-secondary-text-colour;
+    margin: 0 0 $message-type-bottom-spacing 0;
+    padding-left: 0;
     pointer-events: none;
   }
 
 }
 
-#template-list {
-
-  margin-top: govuk-spacing(6);
-
-  &.top-gutter-5px {
-    margin-top: 5px;
-  }
-
-}
-
 .template-list {
 
   &-item {
@@ -123,6 +117,22 @@
 
     }
 
+    &-hint,
+    &-label {
+      padding-left: $message-text-left-spacing;
+    }
+
+    &-label {
+      padding-top: 0px;
+      padding-bottom: 0px;
+    }
+
+    // Fix for GOVUK Frontend selector with high precendence
+    // https://github.com/alphagov/govuk-frontend/blob/v2.13.0/src/components/hint/_hint.scss
+    &-label:not(.govuk-label--m):not(.govuk-label--l):not(.govuk-label--xl)+.template-list-item-hint {
+      margin-bottom: $message-type-bottom-spacing;
+    }
+
   }
 
   &-folder {