Create first tests

[pochka15]

Goal

Implement test scenarios

Scenarios

1. Run coordinator, writer, reader. Expect no applications get blocked, reader prints the received tuple

Notes

• To do this you'd rather create a new Doctest_tests/ScenariosTest.cpp file
• I highly recommend watching this youtube video. There is a chapter about posix_spawn(). I think it is what we need to spawn the processes and wait for them
• Maybe some additional configurations will be needed in the CmakeLists because sometimes functions like posix_spawn don't work out of the box. (Not sure about this)
• See the Makefile to figure out where we run processes from
• Please create a separate branch for this issue

Expected result

make test runs tests and all of them should be passed