Bug 26094: Add class to the "Suggest for purchase" button

Bug 26094: Add class to the "Suggest for purchase" button

Bug 14963 added a new "Suggest for purchase" button on the detail page
of bibliographic records at the OPAC.
This patch adds a specific CSS class to make it reachable easily

Like others button in this action list

Test plan:
Go to the detail page of a bibliographic record at the OPAc
Notice the new CSS class

Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>