gnrc_ipv6_nib: allow for configuration of static link-local addresses
gnrc_ipv6_nib: allow for configuration of static link-local addresses

This feature was removed without replacment in 71a7dbf91856d, but it can
still be useful.

Co-Authored-By: smlng <a0f1490a20d0211c997b44bc357e1972deab8ae3@mlng.net>

OlegHahm/RIOT,x3ro/RIOT,smlng/RIOT,yogo1212/RIOT,kaspar030/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,yogo1212/RIOT,kaspar030/RIOT,authmillenon/RIOT,smlng/RIOT,miri64/RIOT,OlegHahm/RIOT,yogo1212/RIOT,authmillenon/RIOT,x3ro/RIOT,kYc0o/RIOT,x3ro/RIOT,mtausig/RIOT,ant9000/RIOT,ant9000/RIOT,RIOT-OS/RIOT,yogo1212/RIOT,kaspar030/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,smlng/RIOT,authmillenon/RIOT,authmillenon/RIOT,OTAkeys/RIOT,ant9000/RIOT,kYc0o/RIOT,OTAkeys/RIOT,mtausig/RIOT,toonst/RIOT,mtausig/RIOT,kYc0o/RIOT,basilfx/RIOT,jasonatran/RIOT,miri64/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,toonst/RIOT,kYc0o/RIOT,jasonatran/RIOT,ant9000/RIOT,OlegHahm/RIOT,toonst/RIOT,ant9000/RIOT,x3ro/RIOT,OlegHahm/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,smlng/RIOT,miri64/RIOT,toonst/RIOT,x3ro/RIOT,authmillenon/RIOT,basilfx/RIOT,OTAkeys/RIOT,basilfx/RIOT,miri64/RIOT,OTAkeys/RIOT,kaspar030/RIOT,basilfx/RIOT,yogo1212/RIOT,miri64/RIOT,kaspar030/RIOT,jasonatran/RIOT,mtausig/RIOT,basilfx/RIOT,mtausig/RIOT,smlng/RIOT,toonst/RIOT