Lima/add cms toy mt

Note that a recent commit includes renaming cmsToyMT directory as cmsToyGV, as shown in my slides for CMS.

I am suggesting to merge this without rebasing first, because a rebase would put all ~200 toy-mt-framework commits on the same line as GeantV, as if they were part of GeantV development. A merge would keep those commits in a parallel line, marged at the top.

I also have a rebased branch, if you really prefer that route, but at this moment this is not compiling, because of missing FindTBB.cmake and broken CMakeLists.txt files.