NodeTestcases (ts tests) don't run out of process

[eugenschindler]

Since migration to MPS 2020.3, the ts tests don't run out of process. You have to enable "Execute in the same process" in the test run configuration in order to successfully run the test cases, otherwise for every testcase, the testrunner throws a ClassDefNotFoundError exception.

Current working theory is that MPS itself had a regression that broke out of process testruns from MPS 2019 to MPS 2021. To check this assumption, this issue depends on #16 and #17. After those issues have been resolved, we can recheck if the tests then work.