Merge developer configurations into `pyproject.toml`

[redeboer]

Currently, most ComPWA repositories configure their developer tools through separate files. An example would be .mypy.ini and pytest.ini. This makes the main directory of the repositories full of dot-files.

It would be better to merge all these configurations into one pyproject.toml (which is already there for e.g. black). Most developer tools support this, see e.g. here for mypy.

Disadvantages:

• The developer tools were originally configured through separate files, so that it's easier to find their configuration (just open the corresponding file for each tool).
• Language navigation in TOML files seems not to be supported that well in VSCode. For instance, there is no way to navigate sections (e.g. with Ctrl+Shift+O).
• Flake8 does not yet support pyproject.toml: pyproject.toml (PEP 518) support PyCQA/flake8#234 (comment). This issue is resolved, however, by Replace flake8, isort, pydocstyle, and pylint with Ruff #138

Requirements

• Switch to VSCode extension "Even Better Toml" #113
• Create pre-commit hook for TOML taplo formatter #117
• Replace flake8, isort, pydocstyle, and pylint with Ruff #138
• Merge setup.cfg into pyproject.toml #157
• Support taplo configuration in pyproject.toml tamasfe/taplo#603
• Merge tox.ini into pyproject.toml with legacy method #409

[redeboer]

Since PEP 660 (2021), pyproject.toml can replace setup.cfg and setup.py entirely. This does, however, require pip v21.3 in order to install the project in editable mode. However, see pypa/pip#10393 for potential problems with self-depend syntax.