Change test/recipes/95-test_external_oqsprovider.t to allow out-of-source builds

Change test/recipes/95-test_external_oqsprovider.t to allow out-of-source builds

Unfortunately, CMake's FindOpenSSL.cmake module doesn't handle OpenSSL's
build tree very well when it's out-of-source.  This is resolved by create
a local OpenSSL "installation" with a minimum amount of symbolic links,
and using that.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Neil Horman <nhorman@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/28638)