New frontend/backend architecture.

Notes:
* The separation is working pretty well.
* There are a lot of logs printed for all the messaging going on between components, we will disable this before merging this.

Todo:
- [x] forward flags module configured using arguments to the processes.
- [x] remove logs for each communication
- [x] handle SIGINT/SIGTERM in processes
- [x] separate settings in gui-settings and backend-settings
- [x] add changes file

Main changes:
* frontend and backend in different processes
* communication using ZMQ

You can take a look at https://github.com/ivanalejandro0/frontend-backend-zmq-test to see a minimal app using this communication structure.