ticket:10646: Add internal ListFormatter::format method for MeasureFormat.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@35016 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10646: Merge r34990 to r35016 from trunk.

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@35017 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10646: Remove branch

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/tkeep@35023 251d0590-4201-4cf1-90de-194747b24ca1