Bug 11272 - add second submit button to inventory form

Bug 11272 - add second submit button to inventory form

The inventory tool allows for 2 ways of processing files. The first
is to upload a file. The second is to generate the shelf list.
Most libraries think they have to fill in all fields because the
submit button is at the bottom of the second option. They do not.
This patch adds a second submit button under the first method to
make this clearer.

To test:

* Generate a file of barcodes for inventorying
* Before applying the patch use the file upload method to mark as seen
* Apply the patch
* Use the file upload method to mark as seen using the new submit
* Repeat the above for the shelf list method
* Confirm that inventory still works as expected with 2 buttons

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
(cherry picked from commit 40ba1763afc40cd47b23892a3248fd877dc8edce)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>