Add workaround for unavailable SHA1 algorithm for signatures in OpenSSL 3.0, shipped with Centos9 Stream.

Bug: https://github.com/rnpgp/rnp/issues/1595

Bug: https://github.com/rnpgp/rnp/issues/1595

This spares repetitive settings in .github/workflows/, yet keeps
feature enablement in the build system static.

Bug: https://github.com/rnpgp/rnp/issues/1595

Bug: https://github.com/rnpgp/rnp/issues/1595

It doesn't mean all of them are going to work, though.

Enabled Brainpool with OpenSSL backend builds and passes tests.
Enabling SM2 leads to a build failure currently.
Enabling AEAD leads to test failures.
Twofish is not implemented by OpenSSL and there's no intention to have
it in the future, see https://github.com/openssl/openssl/issues/2046

Bug: https://github.com/rnpgp/rnp/issues/1595

Bug: https://github.com/rnpgp/rnp/issues/1595

Fedora 35: OpenSSL backend only, all tests together (no more split
for cli or not), one GCC run and one Clang run in sanitize mode.

Fedora 36: Botan backend only, everything else as above.

Doesn't work yet. To be revisited upon resolution of
https://github.com/riboseinc/yum/issues/9

linux_install_centos9() function is cloned from the "8" counterpart,
but the setup of "powertools" repo has been dropped as it's not
apparently available, and it's not clear which packages was it needed
for.

This combination fails to compile.

Treat it like CentOS 8 for now until we discover the practical
differences.

This combination fails to compile.

Bug: https://github.com/rnpgp/rnp/issues/1617

Bug: https://github.com/rnpgp/rnp/issues/1617