fix(autoaliasattr): search for type aliases under if TYPE_CHECKING

[JasonGrace2282]

Motivation

After #3668 was merged, the module level attributes of manim.mobject.mobject weren't shown
As you can see, this PR fixes that.

Previously, the directive wouldn't find stuff like

from typing import TYPE_CHECKING

if TYPE_CHECKING:
    Updater: TypeAlias = ...

Edge Cases

Please note that these edge cases are unlikely to happen, and are only mentioned for completeness.

TYPE_CHECKING variable

The following will pass the initial filter (it will have to look through the whole body instead of skipping the If node)

TYPE_CHECKING=True
if TYPE_CHECKING:
    ...

This is just a performance thing and not something that can be easily resolved (it's perfectly valid from a Syntax Tree's point of view)

typing.TYPE_CHECKING

The second is this case. I opted to be more specific and only limit it to typing.TYPE_CHECKING. If
there is a consensus to allow the following, it's a one line fix.

import typing as python_typing

if python_typing.TYPE_CHECKING:
    Point2or3D: TypeAlias = Point2D | Point3D

The same edge case as above applies, that is that the following will also have to go through the whole If node:

typing = type('classname', (object,), {'TYPE_CHECKING': True})()
if typing.TYPE_CHECKING:
    ...

[behackl]

I coarsely read the code changes and mainly looked at the rendered documentation -- this seems fine to me. Thanks!