Provider.add_conf_parameter #874

Originally I thought that providers could only be configured through openssl.cnf or environment variables, unlike engines which had engine.ctrl_cmd("MODULE_PATH", path) to achieve that.

But last week I noticed that libp11 (the same one where engine-pkcs11 comes from) implemented another PKCS#11 provider, their documentation now says that OSSL_PROVIDER_load() can be used to load a provider as needed and then OSSL_PROVIDER_add_conf_parameter() can be used to configure it.

ruby-openssl already has OSSL_PROVIDER_load(); would it be possible to also add an OpenSSL::Provider#add_conf_parameter() method that performs OSSL_PROVIDER_add_conf_parameter()?