gh-127248: Fix several issues in the pythoncore.vcxproj.

[smurav]

1. gh-25001: The reference to the parser_interface.h has been deleted. (bpo-43244: Remove parser_interface.h header file #25001)
2. gh-25007: The reference to the pyarena.h has been deleted. (bpo-43244: Remove pyarena.h header #25007)
3. gh-87092: The reference to the pycore_cfg.h has been deleted. This file was mentioned in gh-87092 (move CFG related code from compile.c to flowgraph.c #103021) but it has never been in python/cpython repo (https://github.com/python/cpython/commits/main/Include/internal/pycore_cfg.h)
4. gh-24910: The reference to the symtable.h has been deleted. (bpo-43244: Remove symtable.h header file #24910)
5. gh-20044: The reference to the hashtable.h has been deleted due to the reference to the pycore_hashtable.h exists. (bpo-40602: Rename hashtable.h to pycore_hashtable.h #20044)
6. gh-127248: Reference to zconf.in.h was renamed. Correct name of zconf.in.h is zconf.h.in (https://github.com/python/cpython-source-deps/blob/4dc98e1909830e2bdc2a9cc2236e3c5d5037335b/zconf.h.in)

[zooba]

LGTM so far. pythoncore.vcxproj.filters will probably also have references to these files - do you think you could update/remove those too?

[zooba]

Thanks! I've enabled auto-merge, so hopefully all is clear and it'll just go in.