Introducing testing suite using google test (#4170)

* initial tests for testing Setting<T>

* argg

* keep switch off

* added ci

* fix ci

* merging tests to build.yml

* fixing linux ttests/?

* one more try for ci

* more linux fix for ci

* more ci fixes

* try to fix ctests now

* should fix now

* trying fixing linux tests

* some more tests

* more tests (68 tests) and clang format