Bug 27446: Markup errors in suggestion/suggestion.tt

Bug 27446: Markup errors in suggestion/suggestion.tt

This patch makes various corrections to the suggestions template in the
staff interface:

 - Correct indentation
 - Fix unclosed tags
 - Fix non-unique IDs
 - Add comments to highlight markup structure

To test, apply the patch and test the suggestions interface in the staff
client:

 - Viewing the list of suggestions
 - Viewing the details of a single suggestion
 - Filtering suggestions
 - Organizing suggestions

Test that labels on form controls work correctly, including under each
tab.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>