pantsbuild.pants missing top-level __init__.py causes type checkers to ignore the py.typed marker

[relsunkaev]

Describe the bug
When importing anything from pantsbuild.pants while using strict type checking, an error is reported claiming that the package is missing type stubs. The package is missing a top level __init__.py file, causing type checkers to interpret each package inside pants build.pants as wholly separate and requiring their own py.typed files. This was confirmed with both MyPy and Pyright.

Pants version
pantsbuild.pants==2.12.1rc2

[jsirois]

It looks like we run afoul of the 3rd paragraph here since we do continue to need to ship pants as a namespace package: https://peps.python.org/pep-0561/#packaging-type-information