Make `asyncio.Lock.locked()` return `True` when there are waiters

Bug report

Bug description:

In issue https://github.com/python/cpython/issues/97028 everyone seemed to agree that asyncio.{Lock,Semaphore}.locked() should return True if there are waiters, but this change was implemented only for Semaphore.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-153989

先阅读 asyncio.Lock.locked() 以及 asyncio.Semaphore.locked()，然后查看 issue 97028 以了解已达成一致的语义。开始之前检查已链接的 PR gh-153989，因为其中可能已经包含这项工作；完成条件是：当 lock 存在等待者时，Lock.locked() 返回 True，并提供相应的测试以及针对现有 lock 状态的行为。