Consistently mark types with `| MaybeNone` whenever it is applicable

I noticed that there's a special type alias MaybeNone that represents this specific intent:

We didn't dare to change the type to X | None so instead we changed it to Any

You can find an example in a relatively recent addition of this.

And while this approach makes me very sad, it is good that such cases are marked with MaybeNone, for the purpose of looking at them specially. Maybe some type checker will arise that will have specific handling for it and do something smarter instead.

With that in mind, it would be good to ensure that all such cases are consistently marked.

I noticed at least one case that is not marked like this. It has | Any directly written instead of | MaybeNone. This is in re.match.group*:

https://github.com/python/typeshed/blob/6feca188689e14cdacd8dbf8bc9cf0635993027a/stdlib/re.pyi#L93-L117

从 stdlib/re.pyi 开始，尤其检查第 93–117 行附近的 re.match.group* 定义，并将其与 stdlib/_typeshed/init.pyi 中的 MaybeNone 别名进行比较。检查 stubs 中使用 Any 表示这一意图的类似情况；完成标准是适用的情况都一致改用 MaybeNone，并且没有发现未标记的例外。