MB-8241: Refactor couch_set_view_util module

Refactor all MapReduce View specific code out of the
couch_set_view_util module into the mapreduce_view
module.

Change-Id: I1dd96f4d85fbc4180793ed7b76efda26fb246ac0
Reviewed-on: http://review.couchbase.org/26125
Reviewed-by: Filipe David Borba Manana <fdmanana@gmail.com>
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Tested-by: Volker Mische <volker.mische@gmail.com>