Akin to the successful tst_QStringApiSymmetry, add such a test for generic containers, too. Yes, we have tst_collections, but it's a cut'n'paste mess that makes it hard to systematically perform cross-class checks for consistency. This new test, still in its infancy, uses templates and thus ensures that exactly the same checks are run on all containers. Starting out with front()/back(), which the string classes were found to lack, we will build this test up, as we did and continue to do with the string API one. Change-Id: I07323340b5612ecc658232b2776d788018010d0d Reviewed-by: Lars Knoll <lars.knoll@qt.io>