gh-124218: Use per-thread refcounts for code objects (#125216)

Use per-thread refcounting for the reference from function objects to
their corresponding code object. This can be a source of contention when
frequently creating nested functions. Deferred refcounting alone isn't a
great fit here because these references are on the heap and may be
modified by other libraries.

• Include/cpython/code.h[diff]
• Include/cpython/object.h[diff]
• Include/internal/pycore_object.h[diff]
• Include/internal/pycore_uniqueid.h[diff]
• Objects/codeobject.c[diff]
• Objects/funcobject.c[diff]
• Objects/typeobject.c[diff]
• Python/gc_free_threading.c[diff]
• Python/pylifecycle.c[diff]
• Python/pystate.c[diff]
• Python/uniqueid.c[diff]