Bug 32341: (follow-up) Alternate button style

Bug 32341: (follow-up) Alternate button style

This patch applies a different button style and does a couple of clean
up tasks: Removing the redundant sorting-related CSS and moving the
responsive button CSS to _common.scss where other DataTable-related
styles are found.

I think this different button style is more consistent with the OPAC's
design. It also eliminates untranslatable strings from the CSS.

Signed-off-by: David Cook <dcook@prosentient.com.au>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>