Add uk.macbook.kbd keymap (vt)

PR: 215185
Submitted by: James Wright <james.wright@jigsawdezign.com>
Reported by: James Wright <james.wright@jigsawdezign.com>
Reviewed by: emaste (earlier version)
MFC after: 1 week
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D18395