Fix GH-10000: Test failures when OpenSSL compiled with no-dsa

use sha256 in openssl test suite

Migrate SKIPIF -> EXTENSIONS (#7138)

This is an automated migration of most SKIPIF extension_loaded checks.

Convert resources to objects in ext/openssl

Closes GH-5860

Co-authored-by: Nikita Popov <nikita.ppv@gmail.com>