Bug 32238: Add page-section to label creator pages

Bug 32238: Add page-section to label creator pages

This patch modifies two label creator templates so that a .page-section
container is used to wrap main content.

To test, apply the patch and go to Cataloging -> Label creator.

 - Click Manage -> Label batches.
   - The display of existing batches should look correct.
 - Click "Edit" on one of the label batches.
   - If necessary, submit a set of barcodes or item numbers to add to
     the batch.
   - The display of items in the table of items should look correct.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>