LP#1957179: improve saving of templates in Angular holdings editor

LP#1957179: improve saving of templates in Angular holdings editor

This patch makes the following improvements to the handling
of holding templates in the Angular holdings editor:

- templates are now saved to the cat.copy.templates user setting,
  matching the AngularJS holdings editor
- toast is displayed upon saving or deleting a template
- upon saving a completely new template, re-style it in the
  combobox so that it no longer has the new-and-freetext
  styling

To test
-------
[1] Apply the patch and open the Angular holdings editor.
[2] Verify that once a template is saved or deleted, that
    refreshing the Angular holdings editor will show the
    updated list of templates.
[3] Verify that toast is displayed upon saving or deleting
    a template.

Note that because of a quirk in how user settings are cached by
the web staff client, if you are testing in more than one browser
(but with the same user account), if you save a template in one
browser, you'll need to log out and back in with the second browser
to see the changes.

Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>
Signed-off-by: Michele Morgan <mmorgan@noblenet.org>