Refactor/python migration cleanup

This PR is the last step in the python migration milestone for the library. It includes the next aspects:

A general cleanup in the library, removing all the remanent Sage imports.
Deprecation of the old setup.py and the introduction of the new python standard, pyproject.toml as the file to declare all the metainformation necessary to build the library.
A refactor in the Dockerfile removing the necessity for hardcoding the library dependencies. It preserves the performance on build/rebuild for the docker-commands.
A great refactor and cleanup of the Makefile, as well as the introduction of local commands equivalent to the docker-based ones (make doctests, make doctests-fast, make tests-all, make functional-tests, make kat-tests )

For the pyproject.toml
- Install the library:
```
python3 -m venv .venv
source .venv/bin/activate
pip install .
```
- Look at the accuracy of the information declared in the file.
For the Dockerfile and the Makefile
- Test any command you want (and it would be great if you can test the docker and local version of the commands: make [docker-]doctests, make [docker-]doctests-fast, make [docker-]tests-all, make [docker-]functional-tests, make [docker-]kat-tests .

Crypto-TII / CryptographicEstimators