asyncio module state should be locked with mutexes in free-threaded builds

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Feature or enhancement

Proposal:

Please see issue title.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-121622
• gh-121695
• gh-121774

[colesbury]

I think we also want to make enter_task, leave_task, and swap_current_task behave atomically. For example, enter_task makes two dict API calls that individually lock the dictionary, but the combined operation isn't atomic.

I can think of two strategies for this:

1. Try to replace multiple API calls with a single call. For example, I think enter_task may be able to use PyDict_SetDefaultRef and leave_task may be able to use _PyDict_DelItemIf with some modifications.
2. Use a critical section to lock the dict and use the "lock held" variants.

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Fixed.