adds simple grammar parsing tests

[drbh]

This PR adds simple parsing test to give more insight into the grammar parsing mechanics and expected output.

run tests

mkdir -p build && cd build && cmake ..
cmake --build . --config Release && ./bin/test-grammar-parser

Please let me know if I should make any changes! 🙏

[monatis]

lgtm

There are failing tests that need to be fixed

[drbh]

@monatis should be resolved now. Was missing #include <cassert> header