Fix package creation configuration

[Ferido07]

This change contains:

• package configuration using pyproject.toml instead of setup.py because the standard and recommended method is pyproject.toml
• reorganize structure of code to have better build using the widely used project structuring
• renaming of imports to work for the new structure as well as in a project that imports daffodil
• removed a duplicated test in the main folder

There might be tests which are broken please check.

NOTE The versions I used contains rc1 to avoid name collision when publishing.

How To Test

1. First build the package locally using python3 -m build
2. Publish the package to PyPi using python3 -m twine upload dist/*. Make sure the dist folder only contains the assets of the latest build.
3. Install daffodil (in the project using daffodil) with the exact version just published. For example the existing version if built and uploaded directly will can be installed using pip install daffodil==0.3.0rc1
4. Run test commands and the project should run without ModuleNotFoundError for daffodil

Once verified that everything is working you can change the version in pyproject.toml to 0.3.1, merge this to main branch then finally build and publish the package again.

For more info regarding how to create packages

• https://packaging.python.org/en/latest/tutorials/packaging-projects/
• https://setuptools.pypa.io/en/latest/userguide/pyproject_config.html
• https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#writing-pyproject-toml