Bug 25765: Add GetLoggedInBranchname method

Bug 25765: Add GetLoggedInBranchname method

Add GetLoggedInBranchname method to Branches templates plugin.

Also changes GetName method to use Koha::Library instead of direct SQL.

Test plan :
Run prove t/db_dependent/Template/Plugin/Branches.t

Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
(cherry picked from commit 0fcd0fd2707188368fa5b370b808e875c6ea5814)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>