Add type hints for better mypy support

Hello!

We use mypy to type check our pytest tests. So we have to use wrappers for allure helpers, e.g.

```
from collections.abc import Callable
from typing import Any, TypeVar, cast

import allure

F = TypeVar('F', bound=Callable[..., Any])

def epic(*items: str) -> Callable[[F], F]:
return cast('Callable[[F], F]', allure.epic(*items)) # type: ignore[no-untyped-call]

def tag(*tags: str) -> Callable[[F], F]:
return cast('Callable[[F], F]', allure.tag(*tags)) # type: ignore[no-untyped-call]

... and so on
```
or even use global mute for untyped calls in typed context.

Can you please clarify if there are any plans to introduce type hints into framework?

Thank you.

首先检查 issue 中引用的 allure 辅助 API，以及类型化 pytest 测试中的当前 mypy 错误。明确哪些 framework 辅助函数需要注解，以及覆盖范围应有多大；完成的标准是，类型化测试不再需要为这些未类型化的调用编写 wrapper 函数或进行全局抑制。

由索引模型根据 Issue 内容生成。