Add support for passing the libctx to the config loader

Add support for passing the libctx to the config loader

The self tests for the fips module are triggered on startup and they need to know the
core's libctx in order to function correctly. As the provider can be autoloaded via configuration
it then needs to propagate the callers libctx down to the provider via the config load.

Note that OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CONFIG, ..) is still called, but will only load the default
configuration if the OPENSSL_CONF environment variable is set.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11240)