Enable TC by default and hide

Set up TC so that it is always enabled and defaults to realtime mode.

This allows us to have warp-like functionality without showing
the TC interface, and simplifies a lot of tutorials.  We can still
reconfigure the TC by re-installing the plugin with different settings

index.html

@@ -39,6 +39,7 @@
             openmct.install(openmct.plugins.LocalStorage());
             openmct.install(openmct.plugins.Espresso());
             openmct.install(openmct.plugins.Generator());
+            openmct.install(openmct.plugins.UTCTimeSystem());
             openmct.start();
         });
     </script>