gh-81057: Move the Allocators to _PyRuntimeState

[ericsnowcurrently]

The global allocators were stored in 3 static global variables: _PyMem_Raw, _PyMem, and _PyObject. State for the "small block" allocator was stored in another 13. That makes a total of 16 global variables. We are moving all 16 to the _PyRuntimeState struct as part of the work for gh-81057. (If PEP 684 is accepted then we will follow up by moving them all to PyInterpreterState.)

[bedevere-bot]

:robot: New build scheduled with the buildbot fleet by @ericsnowcurrently for commit 5262207d2f8906bee1c46b3a6f178b2bb0bb4124 :robot:

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.