ENH: Replace the module-level __getattr__ with explicit type annotations

[BvB93]

The main __init__.pyi file currently contains a module-level __getattr__() function and
,while quite convenient due to the incomplete nature of the stubs, its use is rather unsafe:
any getattr(numpy, str(...)) operation is currently considered valid by static type checkers.

For this reason a set of placeholder stubs was recently added to generic/ndarray (#17188) and
all public module (#17104). All that remains is to do the same for the main __init__.pyi file.

TODO

• Remove the module-level __getattr__() function from __init__.pyi.
• Add all objects described in Big list of functions in the top-level namespace missing types #16546 and annotate them as typing.Any.

[ikedaosushi]

I'd like to tackle it if no problem.

[BvB93]

Sure, feel free to go ahead.

[junjunjunk]

@BvB93
May I ask you a question to make sure I'm okay?
The second task means that add describes in __init__.pyi as below?

DataSource: Any
... (other objects)
who: Any

[BvB93]

The second task means that add describes in init.pyi as below?

Yes, exactly like that.
The same as what has been done in the likes of https://github.com/numpy/numpy/blob/master/numpy/char.pyi.

[junjunjunk]

Thank you for your detailed reply.
I issued PR.