Add /on NOTICE_GROUP and /fset NOTICE_GROUP analogous to MSG_GROUP

This hook and format are used for NOTICEs where the destination isn't
a channel and isn't yourself - eg. global targets like $$*.org.  This was
already the case for PRIVMSGs (using the MSG_GROUP hook and format).

Previously these were being routed like a normal NOTICE, and those don't
display the target, so it looked exactly like a private NOTICE to you.

This will also catch server notices sent before you're registered.

include/cset.h

@@ -260,6 +260,7 @@ FORMAT_NICK_MSG_FSET,
 FORMAT_NONICK_FSET,
 FORMAT_NOTE_FSET,
 FORMAT_NOTICE_FSET,
+FORMAT_NOTICE_GROUP_FSET,
 FORMAT_NOTIFY_OFF_FSET,
 FORMAT_NOTIFY_ON_FSET,
 FORMAT_NOTIFY_SIGNOFF_FSET,