Python: Improve pyproject files

The current definition of the .pyproject files is limited.
The only available option is "files"

{
    "files": ["a.py", "b.py", "c.py", ... ]
}

More options could be added to provide better support, like:

• Interpreter location,
• LSP client location,
• main file,
• Resource files,
• UI files,
• etc

Complementary, at some point, the adoption of TOML files by the Python community could lead us to replace the data type. For this, we would require TOML support in Qt.
The general idea is described here: https://git.qt.io/crmaurei/qtoml