Change move folder form to not have default radio btn and to show hint

Updated the move folder form to add a hint for the radio button for the
current folder saying 'current folder'. This hint does not get shown if
you are viewing all folders (so you are not inside a folder).

Also stopped a default radio button from being selected on the form.

app/templates/components/radios.html

@@ -43,11 +43,10 @@
   option_hints={},
   hide_legend=False
 ) %}
-  {% set disable = [current_option_id] %}
   {% call radios_wrapper(
     field, hint, disable, option_hints, hide_legend
   ) %}
-    {{ radio_list(child_map[None], child_map, disable) }}
+    {{ radio_list(child_map[None], child_map, disable, option_hints) }}
   {% endcall %}
 {% endmacro %}