Add a `import type` feature (like typescript)

Importing types can lead to circular imports, longer start up times and unwanted side effects.

I want something like:

from foo.bar import type Baz

def foo(baz: Baz):
    print(baz.bat)

Such that foo, foo.bar and foo.bar.Baz are not actually loaded at all.
It could 'import' the symbol as a forward-ref or some type machinery thing. (maybe just the string "Baz")

Alternatives:

from __future__ import annotations

from typing import TYPE_CHECKING
if TYPE_CHECKING:
    from foo.bar import Baz

def foo(baz: Baz):
    print(baz.bat)

This is mega boilerplate, gross, and leads to messy wacky 'type-time' side effects (https://github.com/python/mypy/issues/11503).

没有指定实现文件、测试或入口点。该提案需要先进行设计和项目上下文方面的工作，新贡献者才能确定代码路径或明确的完成定义。