pythongh-134531: cleanup _hashopenssl.c to support EVP_MAC (python#134626)

Rename components related to `_hashlib.{HASH,HASHXOF}` objects.

- The `EVPobject` structure is renamed `HASHobject`.
- Non-clinic `HASH` methods are now prefixed by `_hashlib_HASH_*`.
  A similar change is made for non-clinic `HASHXOF` methods.
- Functions extracting information from `EVP_MD` objects and functions
  constructing `EVP_MD` objects now include `openssl_evp_md` in their name.

This change allows us to avoid future ambiguities between the `EVP_MD`
and the `EVP_MAC` APIs (currently, we only use `EVP_MD` for hash functions
and rely on the legacy interface for HMAC instead of using `EVP_MAC`).

Author: picnixz

Misc/NEWS.d/next/Library/2025-05-26-11-01-54.gh-issue-134531.my1Fzt.rst

@@ -0,0 +1,2 @@
+:mod:`!_hashlib`: Rename internal C functions for :class:`!_hashlib.HASH`
+and :class:`!_hashlib.HASHXOF` objects. Patch by Bénédikt Tran.