LP#1777677: (follow-up) adjust test message buttons in registration form

LP#1777677: (follow-up) adjust test message buttons in registration form

This patch:

* moves the 'Send Test Email' button in the patron registration form
  to cuddle next to the 'Invalidate' button
* disables the 'Send Test Email' button if the email address is
  changed on the form
* disables the 'Send Test Text' button if the SMS carrier or
  SMS text number is changed on the form

The point of the last two changes is to prevent staff members
from sending a test message prior to saving changes to the email
address or SMS number, as otherwise the test methods would not
have access to the new values.

Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>