GH-127705: Add debug mode for _PyStackRefs inspired by HPy debug mode

[markshannon]

This PR:

• Adds a hashtable to track _PyStackRefs if Py_STACKREF_DEBUG is set.
• Aborts and reports any double-close or leaks of stack refs
• Fixes the leaks found in bytecodes.c by the above

When reporting leaks, both the origin of the _PyStackRef and the last call to PyStackRef_AsPyObjectBorrow are reported.

Only supports the default build for now. It shouldn't be too hard to support free-threading in the future.

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Running on the full test suite passes all but these tests:

Expecting a _PyStackRef to look like a tagged pointer, not an index. Mostly segfaults

test.test_gdb.test_backtrace
test.test_gdb.test_misc
test.test_gdb.test_pretty_print
test_external_inspection

Calling a _PyStackRef... function without holding the GIL at shutdown.

test_faulthandler
test_regrtest

Actual leaks

test.test_multiprocessing_spawn.test_manager
test_repl
test_threading

• Issue: Use tagged pointers on the stack in the default build. #127705