Run or Debug from a Python file's context started it as a script
(`python src/tasks/cli.py`). A module of a package that imports relatively
then fails with "attempted relative import with no known parent package",
and the debugger stops on that exception.
A file with a relative import (`from .x import y`, `from . import x`) now
runs as `python -m <package>.<module>` from the folder its top package sits
in: the last `src` of its path, else the Python project's folder. A
package's `__main__.py` runs as the package. The project's interpreter is
kept (a relative venv path is adjusted to the new working directory), and
the debugger launches it with debugpy's `module`. Files without relative
imports run as scripts as before.
Fixes#1337
l0ng-ai
ebe059e00f