Bug 26958: Move Elasticsearch mapping template JS to the footer

Bug 26958: Move Elasticsearch mapping template JS to the footer

This patch moves inclusion of JavaScript to the footer of the
Elasticsearch mapping template. It also moves the JS into a separate
file.

To test you should have SearchEngine system preference set to
"Elasticsearch."

 - Apply the patch and go to Administration -> Search engine
   configuration (Elasticsearch).
 - Confirm that JavaScript dependent interactions work correctly:
   - Tabs
   - Under the bibliographic records and authorities tabs, table row
     drag-and-drop
   - Under the bibliographic records and authorities tabs, test the
     "Add" line at the bottom of the table.
   - Under the bibliographic records and authorities tabs, test the
     "Delete" button.

Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>