[3.12] gh-108987: Fix _thread.start_new_thread() race condition (#109135) (#110342)

* gh-108987: Fix _thread.start_new_thread() race condition (#109135)

Fix _thread.start_new_thread() race condition. If a thread is created
during Python finalization, the newly spawned thread now exits
immediately instead of trying to access freed memory and lead to a
crash.

thread_run() calls PyEval_AcquireThread() which checks if the thread
must exit. The problem was that tstate was dereferenced earlier in
_PyThreadState_Bind() which leads to a crash most of the time.

Move _PyThreadState_CheckConsistency() from thread_run() to
_PyThreadState_Bind().

(cherry picked from commit 517cd82ea7d01b344804413ef05610934a43a241)

* gh-109795: `_thread.start_new_thread`: allocate thread bootstate using raw memory allocator (#109808)

(cherry picked from commit 1b8f2366b38c87b0450d9c15bdfdd4c4a2fc3a01)

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Co-authored-by: Radislav Chugunov <52372310+chgnrdv@users.noreply.github.com>

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