Bug 28542: Move new authority from Z39.50/SRU to a button

Bug 28542: Move new authority from Z39.50/SRU to a button

Actually in authority tools bar, 'New from Z39.50/SRU' is inside 'New autority' menu.
This is different from biblio cataloguing toolbar, and adds a click to access it.

I propose to move this to its own button.

Test plan :
1) Create a Z39.50/SRU server connexion for authorities
2) Go to authorities home page
3) Check you see buttons 'New autority' and 'New from Z39.50/SRU'
4) Click on 'New autority'
5) Check you only see autority types
6) Click on 'New from Z39.50/SRU'
7) Check you go to Z39.50/SRU popup
8) Delete Z39.50/SRU server connexion for authorities
9) Go to authorities home page
10) Check you dont see 'New from Z39.50/SRU'

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>