LP2017673: Default item alert types

LP2017673: Default item alert types

Also, fix two accessibility issues that nightwatch/axe found

To test:

1. Open your favorite bib record in the angular staff catalog
2. In the item table, choose an item and press Edit
3. Open the Preferences Tab
4. Under the Item Attribute Settings heading, select your favorite item alert type as the default
5. Open the Item Attributes tab.
6. Press the Item Alerts button.
7. Note that your favorite item alert type is now the default.
8. Add various alerts, with a variety of alert types.
9. Press the Apply Changes button.
10. Press the "Apply All, Save & Exit" button
11. Press Edit again
12. Press the Item Alerts button again.
13. Confirm that the correct item alert types are listed.

Signed-off-by: Jane Sandberg <js7389@princeton.edu>
Signed-off-by: Terran McCanna <tmccanna@georgialibraries.org>