Bug 17109: Remove second authentication from (opac-)sendbasket

Bug 17109: Remove second authentication from (opac-)sendbasket

Patch deals with opac and intranet variant.
If we authenticated the first time, it is not necessary to do it
a second time rightaway.

Replaces a call to get_template_and_user (including checkauth) by
gettemplate.

Also removes duplicate use C4::Biblio statements.

Test plan:
[1] Put a few books in the cart.
[2] Send the cart from OPAC.
[3] Send the cart from intranet.

Tested 3 patches together. Works as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>