Add ability to customize file with test driver template
CMake has an ability to generate main() function for tests. Final test binaries can be run in manual mode by choosing testcases interactively or with CTest which can run every testcase in automated mode and report statuses in machine readable format. We want to run tests generated by CMake under operating system which has no fork() support. It means we cannot use CTest. As a temporary solution we replaced template of test driver by our own and run all testcases at once per binary run. It would be good to add ability to customize file with test driver template for such cases.