LP 1907921: Add a patron search button to course admin screen

LP 1907921: Add a patron search button to course admin screen

To test:

1) Apply this patch
2) Go to Admin > Local Admin > Course Reserves List
3) Select a course and Edit it
4) Go to the Course users tab
5) Note that there is now a Search for Patrons button
6) Use this button to search for a patron.
7) Click the select button.
8) Note that the patron's barcode appears in the
Patron Barcode field
9) Select a Role
10) Click the Add User button
11) Note that the patron appears on the Course Users grid

Signed-off-by: Jane Sandberg <sandbej@linnbenton.edu>
Signed-off-by: Garry Collum <gcollum@gmail.com>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>