[6.0] Cassiopeia - Add view-transition for pages (#45786)

* add view-transition for pages
* shorten css declaration

Author: hans2103

build/media_source/templates/site/cassiopeia/scss/blocks/_global.scss

@@ -1,4 +1,10 @@
 // Global
+@media screen and (prefers-reduced-motion: no-preference) {
+  @view-transition {
+    navigation: auto;
+  }
+}
+
 :root {
   scroll-behavior: smooth;
   font-size: $font-size-root;