convert users of build time defaults to use new defaults api

convert users of build time defaults to use new defaults api

Now that we can query for install time registry keys on windows, convert
users of these macros to use the api instead

Add a unit test to validate the functionality of our reg key lookups

Add a test to check to make sure our registry key lookups work.  note
this test only runs on windows (clearly), but also only if the registry
keys are set via an installer or some other manual process (to be done
in the CI workflow)

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/24450)