pythongh-127667: refactor and improve _hashopenssl.c error branches (python#131145)

Refactor `_setException()` into different helpers that can be used separately:

- set_ssl_exception_from_errcode(): set an exception from an explicit SSL error code.
- raise_ssl_error(): set an exception from the last SSL error code or use a user-defined message.
- notify_ssl_error_occurred(): same as raise_ssl_error() but with a generic default message.

# Conflicts:
#	Modules/_hashopenssl.c

Author: picnixz