#150 move dot file generation logic to highway dsl

the dot file generation logic is complex, we need to move it to ../highway_dsl/ module as it's a funcitonality not directly related to workflow engine itself. 1- read and understand ../highway_dsl/ codebase 2- move dotfile generation logic `api/v1/workflows/2f09133f-76e2-4864-8f2a-bb5b5dd57d57/graph/dot`) to highway_dsl 3- install it by creating a wheel (not pip install -e), and test it. simply engine's codebase by using highway_dsl's functionality 4- it can be function to get a python dsl to json and return it's dot file. 5- when done, complete the tests and documentation for highway_dsl and bump it's version get confirmation from me to test.