soma: Expose name via ReadOnlyContainerSpec Whoops. BUG=brillo:730 TEST=unit Change-Id: I9e0e9da16bd15182881f7c623cc04380c0b114b1 Reviewed-on: https://chromium-review.googlesource.com/264067 Trybot-Ready: Chris Masone <cmasone@chromium.org> Tested-by: Chris Masone <cmasone@chromium.org> Reviewed-by: Dan Erat <derat@chromium.org> Commit-Queue: Chris Masone <cmasone@chromium.org>