Bug 28366: Add batch patron modification to patron search results

Bug 28366: Add batch patron modification to patron search results

This patch adds the ability to send selected patrons for batch
modification. It does this by adding a hidden form which is populated
from the borrowernumbers stored in the browser's localStorage when
selections are made.

To test, apply the patch and perform a patron search in the staff client
which will return multiple pages of results.

- Select a patron on the first page of results.
- The "Add to patron list" and "Batch patron modification" buttons
  should become active, and the "Patrons selected" box should show "1"
- After checking another checkbox the "Merge selected patrons" button
  should activate and the "selected" count should increment.
- Test making selections on other pages of results. The "selected" count
  should continue to increment.
- Test the "Batch patron modification" button, confirming that all the
  patrons you selected are correctly passed to the batch patron
  modification tool.
- Test that the "Clear" control works correctly to clear all checkboxes
  and disable all other buttons.
- Test that the "Select all" and "Clear all" controls work correctly,
  enabling all buttons and correctly incrementing the "selected" count.

Signed-off-by: Laura Escamilla <laura.escamilla@bywatersolutions.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>